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The Beck Anxiety Inventory in a non-clinical sample
Behav. Res. Ther. Vol. 33, No. 4, pp. 477~t85, 1995
Pergamon
0005-7967(94)00082-4
THE
BECK ANXIETY NON-CLINICAL
Copyright © 1995 ElsevierScienceLtd Printed in Great Britain. All rights reserved 0005-7967/95 $9.50 + 0.00
INVENTORY
IN A
SAMPLE
MARK CREAMER,* JAMES FORAN and RICHARD BELL Department of Psychology, University of Melbourne, Parkville, Victoria 3052, Australia
(Received 22 April 1994) Summary--This study investigated the properties of the Beck Anxiety Inventory (BAI) in a sample of 326 undergraduate students. Scores on the BAI were compared with data from the State-Trait Anxiety Inventory and the Beck Depression Inventory. The BAI demonstrated good psychometric properties, with a high level of internal consistency. Relatively low test-retest correlations, in comparison with the STAI-Trait, suggested that the scale was functioning as a state measure. Factor analysis revealed a unifactorial solution on the first administration (a time of low stress), but a two factor solution similar to that proposed initially by Beck, Epstein, Brown and Steer (Journal of Consulting and Clinical Psychology, 56, 893-897, 1988) at the second administration (hypothesised to be a time of increased stress). Thus, the two factor structure of the BAI (characterised by physical and cognitive symptoms) may not be distinguishable in the normal population in the absence of an external stressor. An apparent strength of the BAI was its superior ability in differentiating anxiety from depression when compared with the STAI. A combined factor analysis of the BAI and STAI-State revealed two distinct factors, suggesting that the scales may actually be measuring separate, although not necessarily independent, constructs. It is suggested that the high discriminant validity demonstrated by the BAI may have been achieved at the expense of some construct validity.
INTRODUCTION
The psychometric assessment of emotional states has been the focus of considerable attention, with the development of several scales to measure the constructs of anxiety and depression. Attempts to develop self-report inventories to measure anxiety have raised a number of issues regarding the phenomenology of the construct. In particular, the nature of anxiety, issues of state vs trait components, and differentiation from depression have caused several problems for the psychometric evaluation of this emotion. A relatively new scale, the Beck Anxiety Inventory (BAI; Beck, Epstein, Brown & Steer, 1988), shows considerable promise in overcoming some of the problems inherent in earlier scales. Although several studies have been published to date on the properties of the BAI and its interrelationship with other scales, the findings have been inconsistent and, in some cases, contradictory. The aim of the current research was to further investigate the characteristics of the BAI. Following the work of Lang (1971), anxiety is now conceptualised as comprising four major components. In addition to the affective, or emotional, experience of anxiety, it is important also to consider the cognitive, behavioural and physiological elements. Cognitive components comprise impaired cognitive functioning (confusion, poor decision-making, memory problems), as well as fearful thoughts. Such thoughts may relate to the anxiety symptoms themselves (such as "I'm going crazy" or "I'm having a heart attack") or to possible feared outcomes (such as "I'11 make a fool of myself" or "I'!1 get sick"). Behavioural components include agitated movements (such as pacing up and down, wringing hands), as well as attempts to avoid or escape the anxiety-provoking situation. Physiological components of anxiety are characterised by symptoms of hyperarousal, such as sweating, palpitations, muscle tension, and gastro-intestinal symptoms. It is important that any attempt to measure the construct of anxiety adequately addresses each of these symptom groups. *Author for correspondence. 477
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Within the anxiety literature, a distinction is frequently made between trait and state anxiety, with both constructs being conceptualised as multidimensional (Endler & Parker, 1990). The former refers to an underlying vulnerability, a general tendency to experience anxiety symptoms in non-dangerous situations. This trait is thought to show a normal distribution in the general population and is relatively resistant to modification. State anxiety, on the other hand, is conceptualised as a discrete response to a specific, threatening situation. While individuals with high trait anxiety are clearly more vulnerable to experiencing state anxiety, the latter is universally experienced in the face of threat. Thus, situation and person factors interact to determine state anxiety. Psychometric measures of anxiety need to differentiate between state and trait features of the construct. A final issue to be considered in the development of self-report anxiety inventories is the ability to differentiate between anxiety and depression. Clinically, these two constructs show a high degree of overlap (Dobson, 1985; Stavaraki & Vargo, 1986) and it is therefore not surprising that lack of discriminant validity is a common problem for measures of anxiety. Factor analytic studies, using various measures of emotional distress, often capture anxiety and depression on the same factor (Gotlib & Cane, 1989). This finding has lead some authors to suggest that anxiety and depression are actually variants of the same disorder (Stavaraki & Vargo, 1986). However, Dobson (1985), in a review of 16 selected studies using various measures, concluded that anxiety and depression are distinct disorders. He suggested that the problem in distinguishing one from the other was primarily a function of inadequacies in the various self-report scales. Gotlib and Cane (1989) made a similar assessment, pointing specifically to discriminatory deficiency among items in the commonly used measurement scales as a key factor in the reported high correlations between anxiety and depression. However, these authors also make the important observation that " . . . given the overlap in symptoms we should be suspicious of measures of anxiety and depression that do not intercorrelate" (p. 161). This, perhaps, highlights the dilemma faced by psychometricians in the development of such scales. On the one hand, there is a demand for scales that will accurately distinguish between the two constructs; on the other, any instrument that achieves this end is likely to do so at the expense of some construct validity. The State-Trait Anxiety Inventory (STAI; Spielberger, Gorsuch, Lushene, Vagg & Jacobs, 1983) is probably the most widely used measure of anxiety in both clinical and research settings (Gotlib & Cane, 1989). Assessing state and trait anxiety as separate constructs, this instrument shares with other anxiety measures the problem of high correlations with measures of depression (Beck et al., 1988; Tanaka-Matsumi & Kameoka, 1986). It should be noted, however, that both these articles cite Spielberger et al. (1970). This citation refers to form X of the STAI, whereas the currently used version is form Y (Spielberger et al., 1983). The updated version saw 30% of items on form X replaced in order to produce " . . . a 'purer' measure of anxiety that would provide a . . . differential basis of diagnosis of patients suffering from disorders of anxiety and depressive reactions" (Spielberger et al., 1983, p. 2). Interestingly, this is essentially the same reason given by Beck (Beck et al., 1988) for developing the BAI. It remains unclear, therefore, whether criticisms of the STAI as lacking discriminant validity are applicable to the current version. The primary purpose for developing the BAI was to provide a more reliable self-report instrument for discriminating anxiety from depression (Beck et al., 1988). The scale consists of 21 anxiety symptoms, with respondents being asked to indicate the extent to which they were bothered by each item "during the past week, including today". Responses are scored on a 0-3 scale ranging from "not at all" to "severely", giving a score range of 0-63. Beck and Steer (1990) recommend that scores of 0-9 points be interpreted as normal anxiety; 10-18 as mild-moderate; 19-29 as moderate-severe; and 30-63 as severe anxiety. They also suggest that scores for females may be as much as four points higher than for males, and that younger patients score higher than older patients. Although the state/trait issue was not discussed by Beck and his colleagues in the development of the BAI, the time frame suggests that the BAI is more a measure of state, rather than trait, anxiety. The developmental study (Beck et al., 1988), using psychiatric patients, reported a high level of internal consistency (Cronbach's alpha = 0.92) and a good test-retest correlation (r = 0.75) after one week. Factor analysis revealed two factors: "Somatic symptoms" and "Subjective Anxiety and
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Panic Symptoms". However, while all other items on the "Somatic" factor reflect physiological symptoms, the item which loaded second highest on that factor, "Scared", seems more related to items on the "Subjective" factor such as "Fear of the worst happening" and "Terrified". Neither Beck et al. (1988) nor Beck and Steer (1990) commented on this anomaly. A major problem in the development of scales such as the BAI concerns the criteria against which construct validity may be assessed. In the absence of any "gold standard" to measure anxiety, there is a danger that apparent improvements in measurement may simply reflect an alternative definition of the construct. Beck et al. (1988) did not examine the relationship between the BAI and any of the self-report scales for anxiety, even though the STAI and the Zung Self-Rating Anxiety Scale (Zung, 1971) were referred to prominently in comparative comments. They did, however, report a moderate correlation (0.51) between the BAI and the Hamilton Anxiety Rating Scale (HARS; Hamilton, 1959), a clinician-rated measure. While this figure may be considered somewhat low for a coefficient of convergent validity, and perhaps raise questions about the extent to which the BAI and the HARS actually measure the same construct, it may simply reflect different measurement strategies. A low correlation (0.25) with the clinician-rated Hamilton Depression Rating Scale suggested good discrimination for the BAI, but a somewhat higher correlation (0.48) was found between BAI and the self-report Beck Depression Inventory (BDI; Beck, Rush, Shaw & Emery, 1979). Beck et al. (1988) note that this latter correlation is lower than the relationship usually found between the BDI and other self-report anxiety measures. Further evidence of discriminant validity was provided by a factor analysis of the combined BAI and BDI, in which items for each scale loaded separately on two factors (Beck et al., 1988). In recent years, several studies have examined the psychometric properties of the BAI and its relationship to other scales. Much of this research has failed to replicate the original two factor solution for the BAI proposed by Beck et al. (1988). For example, Borden, Peterson and Jackson (1991) found a five factor principal components structure to be optimal, accounting for 60% of variance. The first factor was labelled "Subjective Fear" and included items such as "Fear of the worst happening", "Terrified", and "Scared". The remaining four factors were "Somatic nervousness", "Neurophysiological", "Respiration" and "Muscular/motoric". This factor structure is closer to that found by Beck and Steer (1991) with anxious outpatients; they obtained four factors reflecting neurophysiological, subjective, panic, and autonomic symptoms of anxiety. A recent study using a computer administered version of the BAI with a mixed inpatient sample (Steer, Rissmiller, Ranieri & Beck, 1993) found a two factor structure similar, but not identical, to the original factors proposed by Beck et al. (1988). With regard to validity, Dent and Salkovskis (1986) administered the BAI (then known as the Beck Anxiety Check List--Severity scale) to a non-clinical student sample of 243 Ss and found a high correlation with the BDI (r = 0.61). Fydrich, Dowdall and Chambless (1992) reported results from two clinical populations, comprising 40 and 71 Ss respectively, who had been diagnosed as having D S M - I I I R anxiety disorders. Importantly, a large majority of both samples (75 and 85%, respectively) comprised patients with panic disorder. The authors reported that the BAI discriminated better against the BDI (r = 0.50) than did either the STAI-STATE (r = 0.59) or the STAI-TRAIT (r = 0.73). In addition, they reported relatively low coefficients of convergent validity for the BAI with the STAI-STATE (r = 0.47) and the STAI-TRAIT (r = 0.58). While the authors describe the degree of discrimination achieved by the BAI as remarkable, the low convergent validity again raises questions regarding the extent to which the BAI measures the same construct as other anxiety scales. As with Beck et al. (1988), the authors fail to address this issue adequately. Finally, Beck, Steer and Beck (1993) found the BAI to be useful in differentiating among a sample of 655 clinically anxious outpatients by examining subjective, somatic, and panic subscale scores. Although the BAI was designed primarily for use with clinical samples, the brevity and simplicity of the instrument render it suitable for a range of research paradigms. If the scale is, as claimed, a better measure of anxiety than the STAI, it may increasingly replace the latter as the self-report measure of choice in non-clinical as well as clinical research. It is important, therefore, to examine the properties of this scale with a variety of non-clinical populations. The present study aimed to further investigate the BAI, using larger S numbers than previous studies. The STAI was used as a comparative measure of anxiety, while the BDI was used to gauge the BAI's discriminant validity. BRT 33,4-- I
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METHOD The S group comprised 326 undergraduate students. Ss were predominantly female (73%), with an average age of 21.3 years (SD = 10.2) for males and 19.1 years (SD = 4.1) for females. In order to investigate test-retest reliability under slightly different conditions, scales were administered to all Ss on two occasions with an interval of seven weeks. The first occasion was in the middle of the semester (presumably a time of low stress), while the second testing was conducted in the two weeks prior to examinations. The four questionnaires were presented in booklet form in the following order: BAI; BDI; STAI-STATE; and STAI-TRAIT. Administrations were undertaken in groups of approximately 25 Ss. RESULTS
(a) Descriptive statistics Mean total scores and standard deviations for each scale are shown in Table 1. (A small amount of missing data results in slightly lower S numbers for tests other than the BAI). Using the guidelines for score ranges provided by Beck and Steer (1990), the proportion of Ss with a "normal" anxiety level for time one was 42% (47% for time two); "mild-moderate" anxiety was 35% (35%); "moderate-severe" anxiety was 17% (12%); and "severe" anxiety was 6% (6%). The BAI showed high internal consistency at both administrations, with Cronbach's alpha of 0.91 and 0.90 respectively. The relatively low test-retest correlation (r = 0.62) is not surprising, adding weight to the conceptualisation of the BAI as a state measure. An analysis of variance (ANOVA) was conducted to examine gender effects, using age as a covariate. This analysis revealed a small but significant effect for gender at both time one [F(1,321)= 6.58, P <0.05] and time two [F(1,321) = 9.39, P < 0.01], with females scoring higher than males. There was no effect for age at either time one [F(1,321) = 1.01, P > 0.05] or time two [F(1,321) = 0.79, P > 0.35]. The means and standard deviations for each item on the BAI are included in Table 2; in line with previous authors (e.g. Steer et al., 1993), corrected item-total correlations are also provided. Items with the highest means at both administrations were: "unable to relax", "nervous"; and "fear of the worst happening". The corrected item-total correlations show that, apart from "numbness & tingling" in both tests (r = 0.30 & r = 0.35) and "fear of dying" in the second test (r = 0.34), each item correlated strongly with the total for the other 20 items, a further indication of internal consistency. Most items were relatively consistent across the two administrations; the exception to this was "fear of dying" with a change in item-total correlation of 0.15 from time one to time two.
Co) Factor structure Two factors were extracted using maximum likelihood factor analysis. Although in both the initial and retest factorings the fit of the two factor solution (chi-squares of 635.41 and 555.43, respectively, df = 169) was better than those for a one factor solution (chi-squares of 820.03 and 853.96 respectively, df = 189), the Tucker-Lewis coefficients of reliability (Tucker & Lewis, 1973) were not particularly high (0.76 and 0.81, respectively). It is also clear that the second factoring proved a better fit with respect to these statistics. Although a two factor solution was a better fit
Table I. Means, SD's, Cronbach's alpha and test-retest Correlations of the BAI, BDI, S T A I - S T A T E and S T A I - T R A I T at time one and time two Scale
Mean
SD
Cronbach's alpha
Testretest
BAI (21 items)
Time I (n = 326) Time 2 (n = 326)
13.1 11.8
9.6 9.2
0.91 0.90
0.62
BDI (21 items)
Time I (n = 321) Time 2 (n = 326)
9.1 8.6
7.4 7.3
0.88 0.89
0.79
STAI-State (20 items)
Time 1 (n = 322) Time 2 (n = 324)
38.5 40.1
10.7 10.8
0.94 0.94
0.68
STAI-Trait (20 items)
Time I (n = 323) Time 2 (n = 319)
40.4 39.9
10.7 10.8
0.94 0.94
0.85
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Table 2. Item means, SD's and item-total correlations for the BAt at time one and time two
Item
Time I Mean SD
Time 2 Mean SD
I. 2. 3. 4. 5. 6. 7. 8. 9. 10. I 1. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.
0.27 0.98 0.34 1.30 1.11 0.67 0.89 0.55 0.32 1.26 0.17 0.47 0.51 0.58 0.32 0.26 0.67 0.75 0.35 0.84 0.52
0.30 0.82 0.37 1.21 0.98 0.56 0.70 0.45 0.29 1.27 0.12 0.45 0.48 0.50 0.29 0.16 0.66 0.65 0.31 0.81 0.46
Numbness and tingling Feeling hot Wobbliness in legs Unable to relax Fear of worst happening Dizzy or lightheaded Heart pounding or racing Unsteady Terrified Nervous Feelings of choking Hands trembling Shaky Fear of losing control Difliculty breathing Fear of dying Scared Abdominal discomfort Faint Face flushed Sweating (not due to heat)
0.55 0.78 0.64 0.90 1.05 0.85 0.88 0.77 0.71 0.83 0.53 0.72 0.73 0.91 0.70 0.65 0.80 0.91 0.68 0.88 0.77
0.65 0.76 0.71 0.92 0.97 0.80 0.80 0.69 0.63 0.84 0.44 0.69 0.75 0.84 0.65 0.51 0.77 0.92 0.60 0.83 0.73
Item-total correlations Time I Time 2 0.31 0.50 0.54 0.57 0.62 0.53 0.53 0.64 0.59 0.54 0.48 0.51 0.57 0.60 0.52 0.49 0.58 0.45 0.48 0.48 0.46
0.35 0.48 0.57 0.60 0.56 0.56 0.60 0.68 0.60 0.60 0.44 0.53 0.65 0.60 0.47 0.34 0.57 0.45 0.52 0.48 0.48
in the first testing, oblique rotation (via HYBALL, Rozeboom, 1991) failed to identify a meaningful second factor as only two items ("hands trembling" and "shaky") loaded on the second factor. Accordingly, the one factor solution was adopted for this testing. In each case, because of the problems associated with chi-square as a measure of fit (Tucker & Lewis, 1973), a scree test was used to identify the number of factors. This factor structure is, perhaps, not surprising, given that the sample at time one comprised a normal population under conditions of low stress. The time two administration provides a closer comparison with Beck et al.'s (1988) original sample, since Ss were presumably under some stress given the proximity to their examinations. Factor loadings for the two factor solution at time two are shown in Table 3. This factor structure is similar to that reported by Beck et al. (1988), with the notable difference that "Scared" loads highly (0.85) on the same factor as other cognitive items; this compares with Beck et al.'s (1988) finding that it loads highly (0.76) on the non-cognitive factor. In the first testing, the one factor solution accounted for 35% of the variance while the two factor solution in the retesting accounted for 44%.
Table 3. Two factor solution Ioadings for the BAI at time one, with comparative factors for Beck e t al. (1988a) Item I. 2. 3. 6. 7. 8. 12. 13. 17. 19. 20. 21.
Numbness or tingling Feeling hot Wobbliness in legs Dizzy or lightheaded Heart pounding or racing Unsteady Hands trembling Shaky Scared Faint Face flushed Sweating (not due to heat)
4. Unable to relax 5. Fear of worst happening 9. Terrified 10. Nervous 1 I. Feelings of choking 14. Fear of losing control 15. Difficulty breathing 16. Fear of dying 18. Abdominal discomfort
Time 2 Factor 1 Factor 2 0.52 0.74 0.67 0.71 0.53 0.47 0.82 0.76 0.85 0.58 0.66 0.65
0.43
Beck (1988) Factor 1 Factor 2 0.24 0.65 0.44 0.62 0.42 0.65 0.71 0.82 0.76 0.67 0.67 0.68
0.51 0.72 0.90 0.60 0.30 0.83 0.41 0.60
0.32
Note: Except for Beck (1988), secondary Ioadings < 0.30 are omitted.
0.60 0.87 0.68 0.61 0.32 0.75 0.41 0.41 0.29
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Table 4. Factor loadings for combined BAI and STA1-STATE at time one and time two. Induced two factor solution Item
Time 1 Factor I Factor 2
Time 2 Factor 1 Factor 2
S T A I - S TA TE
15. 16. 10. 20. 5. 8. 2. 19. I. 17. 3. 1I. 7. 4. 18. 6. 14. 12. 9. 13.
Relaxed Content Comfortable Pleasant At ease Satisfied Secure Steady Calm Worried Tense Self-confident Worry about future Strained Confused Upset Indecisive Nervous Frightened Jittery
0.81 0.79 0.78 0.78 0.77 0.77 0.76 0.75 0.68 0.68 0.65 0.62 0.59 0.58 0.57 0.54 0.52 0.50 0.48 0.43
0.33
0.82 0.82 0.71 0.77 0.74 0.75 0.75 0.74 0.70 0.66 0.61 0.67 0.52 0.51 0.51 0.53 0.42 0.56 0.45 0.46
0.34 0.34 0.44
BAI
8. 9. 3. 13. 15. 14. 11. 7. 17. 21. 12. 6. 5. 16. 19. 4. 10. 20. 2. 18. 1.
Unsteady Terrified Wobbliness in legs Shaky Ditficulty breathing Fear of losing control Feelings of choking Heart pounding or racing Scared Sweating (not due to heat) Hands trembling Dizzy or lightheaded Fear of worst happening Fear of dying Faint Unable to relax Nervous Face flushed Feeling hot Indigestion or discomfort Numbness and tingling
0.35
0.37
0.66 0.63 0.62 0.62 0.60 0.60 0.59 0.58 0.58 0.58 0.57 0.57 0.56 0.54 0.53 0.50 0.50 0.49 0.48 0.46 0.35
0.34
0.47
0.42
0.43
0.51 0.46
0.67 0.52 0.66 0.73 0.51 0.47 0.50 0.62 0.47 0.56 0.63 0.62 0.44 0.33 0.56 0.45 0.48 0.52 0.57 0.47 0.42
Note: Loadings < 0.33 have been omitted.
(c) Relationship of the BAI to other scales Correlations between the BAI and the STAI were moderate, (0.56 and 0.64 for the State scale and 0.57 and 0.68 for the Trait scale at times one and two, respectively). Surprisingly, the BAI does not seem to be more closely aligned to the State scale. Inter-test factor analyses were also conducted using the method of maximum likelihood. For both this and the following analysis (with the BDI), solutions were constrained to two factors on a priori grounds, since the alternative hypotheses were that either the tests loaded on the same factor (demonstrating concurrent validity) or they loaded on two factors (indicating a difference in construct between forms). Factor loadings for the combined BAI and STAI-STATE are shown in Table 4. At time one, all of the STAI-STATE items had primary loadings on factor one and all the BAI items had primary loadings on factor two; a similar finding was obtained at time two with the exception of a single BAI item ("unable to relax") which showed a primary loading on factor one. These results strongly suggest that the two scales may be represented by separate (although not necessarily independent) constructs. The BAI had a much lower correlation with the BDI at times one and two (0.54 and 0.63) than did either the STAI-STATE (r = 0.74; t = 0.06, P < 0.001 and r = 0.71; t = 7.34, P < 0.001) or the STAI-TRAIT (r = 0.77; t = 2.82, P < 0.01 and r = 0.78; t = 5.44, P < 0.001), suggesting better discrimination from symptoms of depression. Discriminant validity of the BAI was further explored by factor analysing the combined BAI and BDI scales. The factor loadings are included in Table 5. This two factor solution accounted for 30.3% of the variance at time one and 31.3% at time
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two. In general, BAI items had primary ioadings on the first factor and BDI items (except "weight loss" which did not load greater than 0.25 on either factor) had primary loadings on the second factor. At time two, however, five BAI items showed primary loadings on the second factor; all were from the first BAI factor, characterising the cognitive and affective symptoms. DISCUSSION The results of this study raise a number of issues regarding use of the BAI as a measure of anxiety in the normal population. While the scale appears to show good psychometric properties, with a high level of internal consistency, the question of construct validity--or what the scale is actually measuring--remains a little unclear. With regard to state vs trait anxiety, the wording of the BAI is ambiguous. While the Trait form of the STAI asks Ss to respond as they "generaPy feel" and the State form as they "feel right now", the BAI refers to "the past week". The BAI demonstrated similar correlations with both the State and Trait versions of the STAI. The test-retest correlation for the BAI, however, with an interval of seven weeks, was only moderate (0.62); while comparable with the STAI-State (0.68), this is considerably lower than the test-retest correlation for the STAI-Trait (0.85). This suggests that the BAI may reflect state anxiety and is consistent with its conceptualisation as a measure of current psychopathology rather than more stable personality characteristics.
Table 5. Factor Ioadings for combined BAI and BDI at time one and time two. Induced two factor solution Item
Time 1 Factor 1 Factor 2
Time 2 Factor I Factor 2
BAI
8. 13. 5. 9. 12. 17. 14. 3. 7. 21. 15. 6. 4. 1 I. 10. 20. 2. 19. 16. 18. 1.
Unsteady Shaky Fear of worst happening Terrified Hands trembling Scared Fear of losing control Wobbliness in legs Heart pounding or racing Sweating (not due to heat) Difficulty breathing Dizzy or lightheaded Unable to relax Feelings of choking Nervous Face flushed Feeling hot Faint Fear of dying Abdominal discomfort Numbness or tingling
0.62 0.61 0.59 0.58 0.57 0.56 0.57 0.57 0.56 0,56 0.55 0.54 0.54 0.53 0.52 0.50 0.48 0.48 0.47 0.41 0.29
0.31 0.27
0.32
0,29
0.66 0.73 0.41 0.44 0.65 0.38 0.39 0.64 0.62 0.51 0.41 0.60 0.49 0.41 0.46 0.49 0.54 0.53
0.26 0.39 0.39
0.27 0.43 0.46 0.53 0.60
0.28 0.38 0.45
0.27 0.30
BDI
7. I. 4. 3. 5. 2. 6. 9. 13. 10. 21. 12. 8. 14. 20. 18. 15. 16. 1 I. 17. 19.
Self hate Sadness Dissatisfaction or boredom Failure as a person Guilt Pessimism Being punished Suicide wish Can't make decisions Crying Interest in sex Interest in other people Self-blame Belief about appearance Worry about health Appetite Capacity for work Insomnia Irritation Tiredness Weight loss
0.31 0.28
0.26
0.69 0.66 0.61 0.60 0.57 0.57 0.56 0.53 0.52 0.51 0.51 0.49 0.48 0.47 0.40 0.39 0.38 0.37 0.37 0.35
0.27
0.29
0.34
0.70 0.55 0.56 0.56 0.55 0.47 0.53 0.49 0.61 0.52 0.34 0.45 0.64 0.50 0.32 0.27 0.47 0.41 0.48 045
Note: "Weight Loss" did not load > 0.25 on either factor. Loadings < 0.25 omitted.
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Factor analysis of the BAI resulted in different solutions at times one and two in the current research. At time one, hypothesised to be a period of low stress, a single factor solution provided an adequate account of the data. At the second administration, however, two quite distinct factors appeared in line with Beck et al.'s (1988) original findings. At this time, Ss were thought to be under increased stress and, as such, may more closely resemble a clinical sample. One factor is composed predominantly of cognitive and affective descriptors of anxiety and is closest in content to the STAI. The other factor relates to the psychophysiological concomitants of anxiety. Interestingly, however, the mean total BAI score was not higher at time two (in fact, it was slightly lower than at time one). This suggests a different pattern of responding to the BAI under conditions of increased stress, rather than simply the endorsement of a greater number, or more severe, symptoms. Presumably, the desynchrony between physiological and cognitive symptoms becomes more appaient under such conditions. The important point here is that if the BAI is to be used with large samples of the normal population, it may be unrealistic to expect a factor structure similar to that obtained with a clinical population. As noted earlier, the BAI was developed primarily to establish a simple measure that would discriminate anxiety from depression. The strong emphasis on physiological components (15 of the 21 items relate to physical symptoms) may facilitate better discrimination from depression than earlier anxiety scales. The current study provided some support for the discriminant validity of the BAI. Consistent with the findings of Fydrich, Dowdall and Chambless (1992), the BAI clearly showed lower correlations with the BDI than did either the State or Trait versions of the STAI. Good discriminant validity also implies that the two scales should be identifiable with separate constructs. Factor analysis showed the BAI and the BDI as separate factors, confirming a similar result by Beck et al. (1988). The finding also contrasts with the report by Gotlib and Cane (1989) that, in earlier factor analytic studies, anxiety and depression commonly loaded on the same factor. Those studies, of course, preceded the development of the BAI. The BAI's superiority over the STAI as a discriminant measure is therefore supported by the current results. As noted above, however, this discriminatory power seems to have been achieved in part by a strong focus on the psychophysiological symptoms of anxiety. In clinical terms, it is this aspect of the disorder that most clearly differentiates anxiety from depression. While the BAI taps primarily physiological and cognitive symptoms, the STAI focuses more on affective descriptors. It is therefore not surprising that correlations between the two are relatively low, ranging from 0.56 to 0.68. It is of some concern, however, that the BAI and the STAI appear to measure different, although possibly related, constructs. In the current study, the items of the two scales load on separate factors. While this may be obvious for some items, others appear to be identical in both scales (e.g. "nert, o u s " ) or, at least, highly similar ("relaxed" and "unable to relax"; "frightened" and "terrified") and yet still load on different factors. Unfortunately, the finding that the BAI and STAI are measuring different constructs also raises the possibility that the high discriminant validity of the BAI may have been achieved at the expense of convergent validity. It is possible that, with 15 of the 21 items measuring physiological symptoms, the cognitive, affective and behavioural components of anxiety are accordingly being under-rated by the BAI. Equally, of course, it would be a mistake to conceptualise the STAI as a "benchmark" measure of anxiety; as noted above, that scale correlates highly with depression and it is possible that the BAI actually provides a "cleaner" measure of anxiety. Nevertheless, in clinical terms, this suggests that the BAI may function best in anxiety disorders with a high physiological component such as Panic Disorder and less well in disorders with a stronger cognitive or behavioural component such as Social Phobia or Obsessive-Compulsive Disorder. In this context, the findings of Fydrich et al. (1992) are perhaps not surprising, given that their sample was composed primarily of panic disorder patients. The data reported by Beck and Steer (1990) suggest that mean BAI scores for patients with panic disorder with or without agoraphobia (27.3 and 28.8, respectively) may be up to 11 points higher than other anxiety disorders (e.g. social phobia, 17.8). There is clearly a need to further investigate the performance of the BAI with clinically anxious Ss in general, and specific anxiety disorders in particular. In summary, the BAI seems to be a reliable measure for the assessment of certain aspects of anxiety and provides good discrimination from depression. As such, it may be a useful tool for use with specific disorders. It is possible, however, that the ability of the scale to discriminate from
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depression has been achieved at some expense. The instrument may have a tendency to underrate levels of anxiety in those patients showing desynchrony; that is, low levels of psychophysiologicai symptoms in the context of high levels of pathology in other domains of anxiety. As such, care should be taken when using the BAI in non-clinical samples and in anxiety patients with high levels of cognitive symptoms. REFERENCES Beck, A. T., Epstein, N., Brown, G. & Steer, R. A. (1988). An inventory for measuring clinical anxiety: Psychometric properties. Journal of Consulting and Clinical Psychology, 56, 893-897. Beck, A. T., Rush, A. J., Shaw, B. F. & Emery, G. (1979). Cognitive therapy of depression. New York: Guilford Press. Beck, A. T. & Steer, R. A. (1990). Beck Anxiety Inventory Manual. San Antonio: The Psychological Corporation Harcourt Brace Jovanovich, Inc. Beck, A. T. & Steer, R. A. (1991). Relationship between the Beck Anxiety Inventory and the Hamilton Anxiety Rating Scale with anxious outpatients. Journal of Anxiety Disorders, 5, 213-223. Beck, A. T., Steer, R. & Beck, J. S. (1993). Types of self-reported anxiety in outpatients with DSM-IIIR anxiety disorders. Anxiety, Stress And Coping, 6, 43-55. Borden, J. W., Peterson, D. R. & Jackson, E. A. (1991). The Beck Anxiety Inventory in nonclinical samples: Initial psychometric properties. Journal of Psychopathology and Behavioural Assessment, 13, 345 356. Dent, H. R. & Salkovskis, P. M. (1986). Clinical measures of depression, anxiety, and obsessionality in non-clinical populations. Behaviour Research and Therapy, 24, 689-691. Dobson, K. S. (1985). The relationship between anxiety and depression. Clinical Psychology Review, 5, 307-324. Endler, N. S. & Parker, J. D. (1990). Stress and anxiety: Conceptual and assessment issues. Stress-Medicine, 6, 243-248. Fydrich, T., Dowdall, D. & Chambless, D. L. (1992). Reliability and validity of the Beck Anxiety Inventory. Journal of Anxiety Disorders, 6, 55-61. Gotlib, I. H. & Cane, D. B. (1989). Self-report assessment of depression and anxiety. In Kendall, P. C. & Watson, D. (Eds), Anxiety and depression: Distinctive and overlapping features. (p. 131-169). San Diego: Academic Press. Hamilton, M. (1959). The assessment of anxiety states by rating. British Journal of Medical Psychology, 32, 50-55. Lang, P. J. (1971). The application of psychophysiological methods to the study of psychotherapy and behaviour modification. In Bergin, A. E. & Garfield, S. L. (Eds), Handbook of psychotherapy and behaviour change. New York: Wiley. Rozeboom, W. W. (1991). Hyball: A method for subspace-constrained factor rotation. Multivariate Behavioral Research, 26, 163 177. Spielberger, C. D., Gorsuch, R. L. & Lushene, R. (1970). Manual for State-Trait Anxiety Inventor),. Palo Alto, Califo: Consulting Psychologists Press. Spielberger, C. D., Gorsuch, R. L., Lushene, R., Vagg, P. R. & Jacobs, G. A. (1983). Manual.for the State-Trait Anxiety Inventory (Form Y). Palo Alto, Califo: Consulting Psychologists Press. Stavaraki, C. & Vargo, B. (1986). The relationship of anxiety and depression: A review of the literature. British Journal of Psychiatry, 149, 7-16. Steer, R. A., Rissmiller, D. J., Ranieri, W. F. & Beck, A. T. (1993). Structure of the computer-assisted Beck Anxiety Inventory with psychiatric inpatients. Journal of Personality Assessment, 60, 532 542. Tanaka-Matsumi, J. & Kameoka, V. A. (1986). Reliabilities and concurrent validities of popular self report measures of depression, anxiety and social desirability. Journal of Consulting and Clinical Psychology, 54, 328 333. Tucker, L. R. & Lewis, C. (1973). The reliability coefficient for maximum likelihood factor analysis. Psychometrika, 38, 1 10. Zung, W. (1971). A rating instrument for anxiety disorders. Psychosomatics, 12, 371 379.
Pergamon
0005-7967(94)00082-4
THE
BECK ANXIETY NON-CLINICAL
Copyright © 1995 ElsevierScienceLtd Printed in Great Britain. All rights reserved 0005-7967/95 $9.50 + 0.00
INVENTORY
IN A
SAMPLE
MARK CREAMER,* JAMES FORAN and RICHARD BELL Department of Psychology, University of Melbourne, Parkville, Victoria 3052, Australia
(Received 22 April 1994) Summary--This study investigated the properties of the Beck Anxiety Inventory (BAI) in a sample of 326 undergraduate students. Scores on the BAI were compared with data from the State-Trait Anxiety Inventory and the Beck Depression Inventory. The BAI demonstrated good psychometric properties, with a high level of internal consistency. Relatively low test-retest correlations, in comparison with the STAI-Trait, suggested that the scale was functioning as a state measure. Factor analysis revealed a unifactorial solution on the first administration (a time of low stress), but a two factor solution similar to that proposed initially by Beck, Epstein, Brown and Steer (Journal of Consulting and Clinical Psychology, 56, 893-897, 1988) at the second administration (hypothesised to be a time of increased stress). Thus, the two factor structure of the BAI (characterised by physical and cognitive symptoms) may not be distinguishable in the normal population in the absence of an external stressor. An apparent strength of the BAI was its superior ability in differentiating anxiety from depression when compared with the STAI. A combined factor analysis of the BAI and STAI-State revealed two distinct factors, suggesting that the scales may actually be measuring separate, although not necessarily independent, constructs. It is suggested that the high discriminant validity demonstrated by the BAI may have been achieved at the expense of some construct validity.
INTRODUCTION
The psychometric assessment of emotional states has been the focus of considerable attention, with the development of several scales to measure the constructs of anxiety and depression. Attempts to develop self-report inventories to measure anxiety have raised a number of issues regarding the phenomenology of the construct. In particular, the nature of anxiety, issues of state vs trait components, and differentiation from depression have caused several problems for the psychometric evaluation of this emotion. A relatively new scale, the Beck Anxiety Inventory (BAI; Beck, Epstein, Brown & Steer, 1988), shows considerable promise in overcoming some of the problems inherent in earlier scales. Although several studies have been published to date on the properties of the BAI and its interrelationship with other scales, the findings have been inconsistent and, in some cases, contradictory. The aim of the current research was to further investigate the characteristics of the BAI. Following the work of Lang (1971), anxiety is now conceptualised as comprising four major components. In addition to the affective, or emotional, experience of anxiety, it is important also to consider the cognitive, behavioural and physiological elements. Cognitive components comprise impaired cognitive functioning (confusion, poor decision-making, memory problems), as well as fearful thoughts. Such thoughts may relate to the anxiety symptoms themselves (such as "I'm going crazy" or "I'm having a heart attack") or to possible feared outcomes (such as "I'11 make a fool of myself" or "I'!1 get sick"). Behavioural components include agitated movements (such as pacing up and down, wringing hands), as well as attempts to avoid or escape the anxiety-provoking situation. Physiological components of anxiety are characterised by symptoms of hyperarousal, such as sweating, palpitations, muscle tension, and gastro-intestinal symptoms. It is important that any attempt to measure the construct of anxiety adequately addresses each of these symptom groups. *Author for correspondence. 477
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Mark Creameret al.
Within the anxiety literature, a distinction is frequently made between trait and state anxiety, with both constructs being conceptualised as multidimensional (Endler & Parker, 1990). The former refers to an underlying vulnerability, a general tendency to experience anxiety symptoms in non-dangerous situations. This trait is thought to show a normal distribution in the general population and is relatively resistant to modification. State anxiety, on the other hand, is conceptualised as a discrete response to a specific, threatening situation. While individuals with high trait anxiety are clearly more vulnerable to experiencing state anxiety, the latter is universally experienced in the face of threat. Thus, situation and person factors interact to determine state anxiety. Psychometric measures of anxiety need to differentiate between state and trait features of the construct. A final issue to be considered in the development of self-report anxiety inventories is the ability to differentiate between anxiety and depression. Clinically, these two constructs show a high degree of overlap (Dobson, 1985; Stavaraki & Vargo, 1986) and it is therefore not surprising that lack of discriminant validity is a common problem for measures of anxiety. Factor analytic studies, using various measures of emotional distress, often capture anxiety and depression on the same factor (Gotlib & Cane, 1989). This finding has lead some authors to suggest that anxiety and depression are actually variants of the same disorder (Stavaraki & Vargo, 1986). However, Dobson (1985), in a review of 16 selected studies using various measures, concluded that anxiety and depression are distinct disorders. He suggested that the problem in distinguishing one from the other was primarily a function of inadequacies in the various self-report scales. Gotlib and Cane (1989) made a similar assessment, pointing specifically to discriminatory deficiency among items in the commonly used measurement scales as a key factor in the reported high correlations between anxiety and depression. However, these authors also make the important observation that " . . . given the overlap in symptoms we should be suspicious of measures of anxiety and depression that do not intercorrelate" (p. 161). This, perhaps, highlights the dilemma faced by psychometricians in the development of such scales. On the one hand, there is a demand for scales that will accurately distinguish between the two constructs; on the other, any instrument that achieves this end is likely to do so at the expense of some construct validity. The State-Trait Anxiety Inventory (STAI; Spielberger, Gorsuch, Lushene, Vagg & Jacobs, 1983) is probably the most widely used measure of anxiety in both clinical and research settings (Gotlib & Cane, 1989). Assessing state and trait anxiety as separate constructs, this instrument shares with other anxiety measures the problem of high correlations with measures of depression (Beck et al., 1988; Tanaka-Matsumi & Kameoka, 1986). It should be noted, however, that both these articles cite Spielberger et al. (1970). This citation refers to form X of the STAI, whereas the currently used version is form Y (Spielberger et al., 1983). The updated version saw 30% of items on form X replaced in order to produce " . . . a 'purer' measure of anxiety that would provide a . . . differential basis of diagnosis of patients suffering from disorders of anxiety and depressive reactions" (Spielberger et al., 1983, p. 2). Interestingly, this is essentially the same reason given by Beck (Beck et al., 1988) for developing the BAI. It remains unclear, therefore, whether criticisms of the STAI as lacking discriminant validity are applicable to the current version. The primary purpose for developing the BAI was to provide a more reliable self-report instrument for discriminating anxiety from depression (Beck et al., 1988). The scale consists of 21 anxiety symptoms, with respondents being asked to indicate the extent to which they were bothered by each item "during the past week, including today". Responses are scored on a 0-3 scale ranging from "not at all" to "severely", giving a score range of 0-63. Beck and Steer (1990) recommend that scores of 0-9 points be interpreted as normal anxiety; 10-18 as mild-moderate; 19-29 as moderate-severe; and 30-63 as severe anxiety. They also suggest that scores for females may be as much as four points higher than for males, and that younger patients score higher than older patients. Although the state/trait issue was not discussed by Beck and his colleagues in the development of the BAI, the time frame suggests that the BAI is more a measure of state, rather than trait, anxiety. The developmental study (Beck et al., 1988), using psychiatric patients, reported a high level of internal consistency (Cronbach's alpha = 0.92) and a good test-retest correlation (r = 0.75) after one week. Factor analysis revealed two factors: "Somatic symptoms" and "Subjective Anxiety and
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Panic Symptoms". However, while all other items on the "Somatic" factor reflect physiological symptoms, the item which loaded second highest on that factor, "Scared", seems more related to items on the "Subjective" factor such as "Fear of the worst happening" and "Terrified". Neither Beck et al. (1988) nor Beck and Steer (1990) commented on this anomaly. A major problem in the development of scales such as the BAI concerns the criteria against which construct validity may be assessed. In the absence of any "gold standard" to measure anxiety, there is a danger that apparent improvements in measurement may simply reflect an alternative definition of the construct. Beck et al. (1988) did not examine the relationship between the BAI and any of the self-report scales for anxiety, even though the STAI and the Zung Self-Rating Anxiety Scale (Zung, 1971) were referred to prominently in comparative comments. They did, however, report a moderate correlation (0.51) between the BAI and the Hamilton Anxiety Rating Scale (HARS; Hamilton, 1959), a clinician-rated measure. While this figure may be considered somewhat low for a coefficient of convergent validity, and perhaps raise questions about the extent to which the BAI and the HARS actually measure the same construct, it may simply reflect different measurement strategies. A low correlation (0.25) with the clinician-rated Hamilton Depression Rating Scale suggested good discrimination for the BAI, but a somewhat higher correlation (0.48) was found between BAI and the self-report Beck Depression Inventory (BDI; Beck, Rush, Shaw & Emery, 1979). Beck et al. (1988) note that this latter correlation is lower than the relationship usually found between the BDI and other self-report anxiety measures. Further evidence of discriminant validity was provided by a factor analysis of the combined BAI and BDI, in which items for each scale loaded separately on two factors (Beck et al., 1988). In recent years, several studies have examined the psychometric properties of the BAI and its relationship to other scales. Much of this research has failed to replicate the original two factor solution for the BAI proposed by Beck et al. (1988). For example, Borden, Peterson and Jackson (1991) found a five factor principal components structure to be optimal, accounting for 60% of variance. The first factor was labelled "Subjective Fear" and included items such as "Fear of the worst happening", "Terrified", and "Scared". The remaining four factors were "Somatic nervousness", "Neurophysiological", "Respiration" and "Muscular/motoric". This factor structure is closer to that found by Beck and Steer (1991) with anxious outpatients; they obtained four factors reflecting neurophysiological, subjective, panic, and autonomic symptoms of anxiety. A recent study using a computer administered version of the BAI with a mixed inpatient sample (Steer, Rissmiller, Ranieri & Beck, 1993) found a two factor structure similar, but not identical, to the original factors proposed by Beck et al. (1988). With regard to validity, Dent and Salkovskis (1986) administered the BAI (then known as the Beck Anxiety Check List--Severity scale) to a non-clinical student sample of 243 Ss and found a high correlation with the BDI (r = 0.61). Fydrich, Dowdall and Chambless (1992) reported results from two clinical populations, comprising 40 and 71 Ss respectively, who had been diagnosed as having D S M - I I I R anxiety disorders. Importantly, a large majority of both samples (75 and 85%, respectively) comprised patients with panic disorder. The authors reported that the BAI discriminated better against the BDI (r = 0.50) than did either the STAI-STATE (r = 0.59) or the STAI-TRAIT (r = 0.73). In addition, they reported relatively low coefficients of convergent validity for the BAI with the STAI-STATE (r = 0.47) and the STAI-TRAIT (r = 0.58). While the authors describe the degree of discrimination achieved by the BAI as remarkable, the low convergent validity again raises questions regarding the extent to which the BAI measures the same construct as other anxiety scales. As with Beck et al. (1988), the authors fail to address this issue adequately. Finally, Beck, Steer and Beck (1993) found the BAI to be useful in differentiating among a sample of 655 clinically anxious outpatients by examining subjective, somatic, and panic subscale scores. Although the BAI was designed primarily for use with clinical samples, the brevity and simplicity of the instrument render it suitable for a range of research paradigms. If the scale is, as claimed, a better measure of anxiety than the STAI, it may increasingly replace the latter as the self-report measure of choice in non-clinical as well as clinical research. It is important, therefore, to examine the properties of this scale with a variety of non-clinical populations. The present study aimed to further investigate the BAI, using larger S numbers than previous studies. The STAI was used as a comparative measure of anxiety, while the BDI was used to gauge the BAI's discriminant validity. BRT 33,4-- I
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METHOD The S group comprised 326 undergraduate students. Ss were predominantly female (73%), with an average age of 21.3 years (SD = 10.2) for males and 19.1 years (SD = 4.1) for females. In order to investigate test-retest reliability under slightly different conditions, scales were administered to all Ss on two occasions with an interval of seven weeks. The first occasion was in the middle of the semester (presumably a time of low stress), while the second testing was conducted in the two weeks prior to examinations. The four questionnaires were presented in booklet form in the following order: BAI; BDI; STAI-STATE; and STAI-TRAIT. Administrations were undertaken in groups of approximately 25 Ss. RESULTS
(a) Descriptive statistics Mean total scores and standard deviations for each scale are shown in Table 1. (A small amount of missing data results in slightly lower S numbers for tests other than the BAI). Using the guidelines for score ranges provided by Beck and Steer (1990), the proportion of Ss with a "normal" anxiety level for time one was 42% (47% for time two); "mild-moderate" anxiety was 35% (35%); "moderate-severe" anxiety was 17% (12%); and "severe" anxiety was 6% (6%). The BAI showed high internal consistency at both administrations, with Cronbach's alpha of 0.91 and 0.90 respectively. The relatively low test-retest correlation (r = 0.62) is not surprising, adding weight to the conceptualisation of the BAI as a state measure. An analysis of variance (ANOVA) was conducted to examine gender effects, using age as a covariate. This analysis revealed a small but significant effect for gender at both time one [F(1,321)= 6.58, P <0.05] and time two [F(1,321) = 9.39, P < 0.01], with females scoring higher than males. There was no effect for age at either time one [F(1,321) = 1.01, P > 0.05] or time two [F(1,321) = 0.79, P > 0.35]. The means and standard deviations for each item on the BAI are included in Table 2; in line with previous authors (e.g. Steer et al., 1993), corrected item-total correlations are also provided. Items with the highest means at both administrations were: "unable to relax", "nervous"; and "fear of the worst happening". The corrected item-total correlations show that, apart from "numbness & tingling" in both tests (r = 0.30 & r = 0.35) and "fear of dying" in the second test (r = 0.34), each item correlated strongly with the total for the other 20 items, a further indication of internal consistency. Most items were relatively consistent across the two administrations; the exception to this was "fear of dying" with a change in item-total correlation of 0.15 from time one to time two.
Co) Factor structure Two factors were extracted using maximum likelihood factor analysis. Although in both the initial and retest factorings the fit of the two factor solution (chi-squares of 635.41 and 555.43, respectively, df = 169) was better than those for a one factor solution (chi-squares of 820.03 and 853.96 respectively, df = 189), the Tucker-Lewis coefficients of reliability (Tucker & Lewis, 1973) were not particularly high (0.76 and 0.81, respectively). It is also clear that the second factoring proved a better fit with respect to these statistics. Although a two factor solution was a better fit
Table I. Means, SD's, Cronbach's alpha and test-retest Correlations of the BAI, BDI, S T A I - S T A T E and S T A I - T R A I T at time one and time two Scale
Mean
SD
Cronbach's alpha
Testretest
BAI (21 items)
Time I (n = 326) Time 2 (n = 326)
13.1 11.8
9.6 9.2
0.91 0.90
0.62
BDI (21 items)
Time I (n = 321) Time 2 (n = 326)
9.1 8.6
7.4 7.3
0.88 0.89
0.79
STAI-State (20 items)
Time 1 (n = 322) Time 2 (n = 324)
38.5 40.1
10.7 10.8
0.94 0.94
0.68
STAI-Trait (20 items)
Time I (n = 323) Time 2 (n = 319)
40.4 39.9
10.7 10.8
0.94 0.94
0.85
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Table 2. Item means, SD's and item-total correlations for the BAt at time one and time two
Item
Time I Mean SD
Time 2 Mean SD
I. 2. 3. 4. 5. 6. 7. 8. 9. 10. I 1. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.
0.27 0.98 0.34 1.30 1.11 0.67 0.89 0.55 0.32 1.26 0.17 0.47 0.51 0.58 0.32 0.26 0.67 0.75 0.35 0.84 0.52
0.30 0.82 0.37 1.21 0.98 0.56 0.70 0.45 0.29 1.27 0.12 0.45 0.48 0.50 0.29 0.16 0.66 0.65 0.31 0.81 0.46
Numbness and tingling Feeling hot Wobbliness in legs Unable to relax Fear of worst happening Dizzy or lightheaded Heart pounding or racing Unsteady Terrified Nervous Feelings of choking Hands trembling Shaky Fear of losing control Difliculty breathing Fear of dying Scared Abdominal discomfort Faint Face flushed Sweating (not due to heat)
0.55 0.78 0.64 0.90 1.05 0.85 0.88 0.77 0.71 0.83 0.53 0.72 0.73 0.91 0.70 0.65 0.80 0.91 0.68 0.88 0.77
0.65 0.76 0.71 0.92 0.97 0.80 0.80 0.69 0.63 0.84 0.44 0.69 0.75 0.84 0.65 0.51 0.77 0.92 0.60 0.83 0.73
Item-total correlations Time I Time 2 0.31 0.50 0.54 0.57 0.62 0.53 0.53 0.64 0.59 0.54 0.48 0.51 0.57 0.60 0.52 0.49 0.58 0.45 0.48 0.48 0.46
0.35 0.48 0.57 0.60 0.56 0.56 0.60 0.68 0.60 0.60 0.44 0.53 0.65 0.60 0.47 0.34 0.57 0.45 0.52 0.48 0.48
in the first testing, oblique rotation (via HYBALL, Rozeboom, 1991) failed to identify a meaningful second factor as only two items ("hands trembling" and "shaky") loaded on the second factor. Accordingly, the one factor solution was adopted for this testing. In each case, because of the problems associated with chi-square as a measure of fit (Tucker & Lewis, 1973), a scree test was used to identify the number of factors. This factor structure is, perhaps, not surprising, given that the sample at time one comprised a normal population under conditions of low stress. The time two administration provides a closer comparison with Beck et al.'s (1988) original sample, since Ss were presumably under some stress given the proximity to their examinations. Factor loadings for the two factor solution at time two are shown in Table 3. This factor structure is similar to that reported by Beck et al. (1988), with the notable difference that "Scared" loads highly (0.85) on the same factor as other cognitive items; this compares with Beck et al.'s (1988) finding that it loads highly (0.76) on the non-cognitive factor. In the first testing, the one factor solution accounted for 35% of the variance while the two factor solution in the retesting accounted for 44%.
Table 3. Two factor solution Ioadings for the BAI at time one, with comparative factors for Beck e t al. (1988a) Item I. 2. 3. 6. 7. 8. 12. 13. 17. 19. 20. 21.
Numbness or tingling Feeling hot Wobbliness in legs Dizzy or lightheaded Heart pounding or racing Unsteady Hands trembling Shaky Scared Faint Face flushed Sweating (not due to heat)
4. Unable to relax 5. Fear of worst happening 9. Terrified 10. Nervous 1 I. Feelings of choking 14. Fear of losing control 15. Difficulty breathing 16. Fear of dying 18. Abdominal discomfort
Time 2 Factor 1 Factor 2 0.52 0.74 0.67 0.71 0.53 0.47 0.82 0.76 0.85 0.58 0.66 0.65
0.43
Beck (1988) Factor 1 Factor 2 0.24 0.65 0.44 0.62 0.42 0.65 0.71 0.82 0.76 0.67 0.67 0.68
0.51 0.72 0.90 0.60 0.30 0.83 0.41 0.60
0.32
Note: Except for Beck (1988), secondary Ioadings < 0.30 are omitted.
0.60 0.87 0.68 0.61 0.32 0.75 0.41 0.41 0.29
M a r k Creamer e t a l .
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Table 4. Factor loadings for combined BAI and STA1-STATE at time one and time two. Induced two factor solution Item
Time 1 Factor I Factor 2
Time 2 Factor 1 Factor 2
S T A I - S TA TE
15. 16. 10. 20. 5. 8. 2. 19. I. 17. 3. 1I. 7. 4. 18. 6. 14. 12. 9. 13.
Relaxed Content Comfortable Pleasant At ease Satisfied Secure Steady Calm Worried Tense Self-confident Worry about future Strained Confused Upset Indecisive Nervous Frightened Jittery
0.81 0.79 0.78 0.78 0.77 0.77 0.76 0.75 0.68 0.68 0.65 0.62 0.59 0.58 0.57 0.54 0.52 0.50 0.48 0.43
0.33
0.82 0.82 0.71 0.77 0.74 0.75 0.75 0.74 0.70 0.66 0.61 0.67 0.52 0.51 0.51 0.53 0.42 0.56 0.45 0.46
0.34 0.34 0.44
BAI
8. 9. 3. 13. 15. 14. 11. 7. 17. 21. 12. 6. 5. 16. 19. 4. 10. 20. 2. 18. 1.
Unsteady Terrified Wobbliness in legs Shaky Ditficulty breathing Fear of losing control Feelings of choking Heart pounding or racing Scared Sweating (not due to heat) Hands trembling Dizzy or lightheaded Fear of worst happening Fear of dying Faint Unable to relax Nervous Face flushed Feeling hot Indigestion or discomfort Numbness and tingling
0.35
0.37
0.66 0.63 0.62 0.62 0.60 0.60 0.59 0.58 0.58 0.58 0.57 0.57 0.56 0.54 0.53 0.50 0.50 0.49 0.48 0.46 0.35
0.34
0.47
0.42
0.43
0.51 0.46
0.67 0.52 0.66 0.73 0.51 0.47 0.50 0.62 0.47 0.56 0.63 0.62 0.44 0.33 0.56 0.45 0.48 0.52 0.57 0.47 0.42
Note: Loadings < 0.33 have been omitted.
(c) Relationship of the BAI to other scales Correlations between the BAI and the STAI were moderate, (0.56 and 0.64 for the State scale and 0.57 and 0.68 for the Trait scale at times one and two, respectively). Surprisingly, the BAI does not seem to be more closely aligned to the State scale. Inter-test factor analyses were also conducted using the method of maximum likelihood. For both this and the following analysis (with the BDI), solutions were constrained to two factors on a priori grounds, since the alternative hypotheses were that either the tests loaded on the same factor (demonstrating concurrent validity) or they loaded on two factors (indicating a difference in construct between forms). Factor loadings for the combined BAI and STAI-STATE are shown in Table 4. At time one, all of the STAI-STATE items had primary loadings on factor one and all the BAI items had primary loadings on factor two; a similar finding was obtained at time two with the exception of a single BAI item ("unable to relax") which showed a primary loading on factor one. These results strongly suggest that the two scales may be represented by separate (although not necessarily independent) constructs. The BAI had a much lower correlation with the BDI at times one and two (0.54 and 0.63) than did either the STAI-STATE (r = 0.74; t = 0.06, P < 0.001 and r = 0.71; t = 7.34, P < 0.001) or the STAI-TRAIT (r = 0.77; t = 2.82, P < 0.01 and r = 0.78; t = 5.44, P < 0.001), suggesting better discrimination from symptoms of depression. Discriminant validity of the BAI was further explored by factor analysing the combined BAI and BDI scales. The factor loadings are included in Table 5. This two factor solution accounted for 30.3% of the variance at time one and 31.3% at time
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two. In general, BAI items had primary ioadings on the first factor and BDI items (except "weight loss" which did not load greater than 0.25 on either factor) had primary loadings on the second factor. At time two, however, five BAI items showed primary loadings on the second factor; all were from the first BAI factor, characterising the cognitive and affective symptoms. DISCUSSION The results of this study raise a number of issues regarding use of the BAI as a measure of anxiety in the normal population. While the scale appears to show good psychometric properties, with a high level of internal consistency, the question of construct validity--or what the scale is actually measuring--remains a little unclear. With regard to state vs trait anxiety, the wording of the BAI is ambiguous. While the Trait form of the STAI asks Ss to respond as they "generaPy feel" and the State form as they "feel right now", the BAI refers to "the past week". The BAI demonstrated similar correlations with both the State and Trait versions of the STAI. The test-retest correlation for the BAI, however, with an interval of seven weeks, was only moderate (0.62); while comparable with the STAI-State (0.68), this is considerably lower than the test-retest correlation for the STAI-Trait (0.85). This suggests that the BAI may reflect state anxiety and is consistent with its conceptualisation as a measure of current psychopathology rather than more stable personality characteristics.
Table 5. Factor Ioadings for combined BAI and BDI at time one and time two. Induced two factor solution Item
Time 1 Factor 1 Factor 2
Time 2 Factor I Factor 2
BAI
8. 13. 5. 9. 12. 17. 14. 3. 7. 21. 15. 6. 4. 1 I. 10. 20. 2. 19. 16. 18. 1.
Unsteady Shaky Fear of worst happening Terrified Hands trembling Scared Fear of losing control Wobbliness in legs Heart pounding or racing Sweating (not due to heat) Difficulty breathing Dizzy or lightheaded Unable to relax Feelings of choking Nervous Face flushed Feeling hot Faint Fear of dying Abdominal discomfort Numbness or tingling
0.62 0.61 0.59 0.58 0.57 0.56 0.57 0.57 0.56 0,56 0.55 0.54 0.54 0.53 0.52 0.50 0.48 0.48 0.47 0.41 0.29
0.31 0.27
0.32
0,29
0.66 0.73 0.41 0.44 0.65 0.38 0.39 0.64 0.62 0.51 0.41 0.60 0.49 0.41 0.46 0.49 0.54 0.53
0.26 0.39 0.39
0.27 0.43 0.46 0.53 0.60
0.28 0.38 0.45
0.27 0.30
BDI
7. I. 4. 3. 5. 2. 6. 9. 13. 10. 21. 12. 8. 14. 20. 18. 15. 16. 1 I. 17. 19.
Self hate Sadness Dissatisfaction or boredom Failure as a person Guilt Pessimism Being punished Suicide wish Can't make decisions Crying Interest in sex Interest in other people Self-blame Belief about appearance Worry about health Appetite Capacity for work Insomnia Irritation Tiredness Weight loss
0.31 0.28
0.26
0.69 0.66 0.61 0.60 0.57 0.57 0.56 0.53 0.52 0.51 0.51 0.49 0.48 0.47 0.40 0.39 0.38 0.37 0.37 0.35
0.27
0.29
0.34
0.70 0.55 0.56 0.56 0.55 0.47 0.53 0.49 0.61 0.52 0.34 0.45 0.64 0.50 0.32 0.27 0.47 0.41 0.48 045
Note: "Weight Loss" did not load > 0.25 on either factor. Loadings < 0.25 omitted.
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Factor analysis of the BAI resulted in different solutions at times one and two in the current research. At time one, hypothesised to be a period of low stress, a single factor solution provided an adequate account of the data. At the second administration, however, two quite distinct factors appeared in line with Beck et al.'s (1988) original findings. At this time, Ss were thought to be under increased stress and, as such, may more closely resemble a clinical sample. One factor is composed predominantly of cognitive and affective descriptors of anxiety and is closest in content to the STAI. The other factor relates to the psychophysiological concomitants of anxiety. Interestingly, however, the mean total BAI score was not higher at time two (in fact, it was slightly lower than at time one). This suggests a different pattern of responding to the BAI under conditions of increased stress, rather than simply the endorsement of a greater number, or more severe, symptoms. Presumably, the desynchrony between physiological and cognitive symptoms becomes more appaient under such conditions. The important point here is that if the BAI is to be used with large samples of the normal population, it may be unrealistic to expect a factor structure similar to that obtained with a clinical population. As noted earlier, the BAI was developed primarily to establish a simple measure that would discriminate anxiety from depression. The strong emphasis on physiological components (15 of the 21 items relate to physical symptoms) may facilitate better discrimination from depression than earlier anxiety scales. The current study provided some support for the discriminant validity of the BAI. Consistent with the findings of Fydrich, Dowdall and Chambless (1992), the BAI clearly showed lower correlations with the BDI than did either the State or Trait versions of the STAI. Good discriminant validity also implies that the two scales should be identifiable with separate constructs. Factor analysis showed the BAI and the BDI as separate factors, confirming a similar result by Beck et al. (1988). The finding also contrasts with the report by Gotlib and Cane (1989) that, in earlier factor analytic studies, anxiety and depression commonly loaded on the same factor. Those studies, of course, preceded the development of the BAI. The BAI's superiority over the STAI as a discriminant measure is therefore supported by the current results. As noted above, however, this discriminatory power seems to have been achieved in part by a strong focus on the psychophysiological symptoms of anxiety. In clinical terms, it is this aspect of the disorder that most clearly differentiates anxiety from depression. While the BAI taps primarily physiological and cognitive symptoms, the STAI focuses more on affective descriptors. It is therefore not surprising that correlations between the two are relatively low, ranging from 0.56 to 0.68. It is of some concern, however, that the BAI and the STAI appear to measure different, although possibly related, constructs. In the current study, the items of the two scales load on separate factors. While this may be obvious for some items, others appear to be identical in both scales (e.g. "nert, o u s " ) or, at least, highly similar ("relaxed" and "unable to relax"; "frightened" and "terrified") and yet still load on different factors. Unfortunately, the finding that the BAI and STAI are measuring different constructs also raises the possibility that the high discriminant validity of the BAI may have been achieved at the expense of convergent validity. It is possible that, with 15 of the 21 items measuring physiological symptoms, the cognitive, affective and behavioural components of anxiety are accordingly being under-rated by the BAI. Equally, of course, it would be a mistake to conceptualise the STAI as a "benchmark" measure of anxiety; as noted above, that scale correlates highly with depression and it is possible that the BAI actually provides a "cleaner" measure of anxiety. Nevertheless, in clinical terms, this suggests that the BAI may function best in anxiety disorders with a high physiological component such as Panic Disorder and less well in disorders with a stronger cognitive or behavioural component such as Social Phobia or Obsessive-Compulsive Disorder. In this context, the findings of Fydrich et al. (1992) are perhaps not surprising, given that their sample was composed primarily of panic disorder patients. The data reported by Beck and Steer (1990) suggest that mean BAI scores for patients with panic disorder with or without agoraphobia (27.3 and 28.8, respectively) may be up to 11 points higher than other anxiety disorders (e.g. social phobia, 17.8). There is clearly a need to further investigate the performance of the BAI with clinically anxious Ss in general, and specific anxiety disorders in particular. In summary, the BAI seems to be a reliable measure for the assessment of certain aspects of anxiety and provides good discrimination from depression. As such, it may be a useful tool for use with specific disorders. It is possible, however, that the ability of the scale to discriminate from
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depression has been achieved at some expense. The instrument may have a tendency to underrate levels of anxiety in those patients showing desynchrony; that is, low levels of psychophysiologicai symptoms in the context of high levels of pathology in other domains of anxiety. As such, care should be taken when using the BAI in non-clinical samples and in anxiety patients with high levels of cognitive symptoms. REFERENCES Beck, A. T., Epstein, N., Brown, G. & Steer, R. A. (1988). An inventory for measuring clinical anxiety: Psychometric properties. Journal of Consulting and Clinical Psychology, 56, 893-897. Beck, A. T., Rush, A. J., Shaw, B. F. & Emery, G. (1979). Cognitive therapy of depression. New York: Guilford Press. Beck, A. T. & Steer, R. A. (1990). Beck Anxiety Inventory Manual. San Antonio: The Psychological Corporation Harcourt Brace Jovanovich, Inc. Beck, A. T. & Steer, R. A. (1991). Relationship between the Beck Anxiety Inventory and the Hamilton Anxiety Rating Scale with anxious outpatients. Journal of Anxiety Disorders, 5, 213-223. Beck, A. T., Steer, R. & Beck, J. S. (1993). Types of self-reported anxiety in outpatients with DSM-IIIR anxiety disorders. Anxiety, Stress And Coping, 6, 43-55. Borden, J. W., Peterson, D. R. & Jackson, E. A. (1991). The Beck Anxiety Inventory in nonclinical samples: Initial psychometric properties. Journal of Psychopathology and Behavioural Assessment, 13, 345 356. Dent, H. R. & Salkovskis, P. M. (1986). Clinical measures of depression, anxiety, and obsessionality in non-clinical populations. Behaviour Research and Therapy, 24, 689-691. Dobson, K. S. (1985). The relationship between anxiety and depression. Clinical Psychology Review, 5, 307-324. Endler, N. S. & Parker, J. D. (1990). Stress and anxiety: Conceptual and assessment issues. Stress-Medicine, 6, 243-248. Fydrich, T., Dowdall, D. & Chambless, D. L. (1992). Reliability and validity of the Beck Anxiety Inventory. Journal of Anxiety Disorders, 6, 55-61. Gotlib, I. H. & Cane, D. B. (1989). Self-report assessment of depression and anxiety. In Kendall, P. C. & Watson, D. (Eds), Anxiety and depression: Distinctive and overlapping features. (p. 131-169). San Diego: Academic Press. Hamilton, M. (1959). The assessment of anxiety states by rating. British Journal of Medical Psychology, 32, 50-55. Lang, P. J. (1971). The application of psychophysiological methods to the study of psychotherapy and behaviour modification. In Bergin, A. E. & Garfield, S. L. (Eds), Handbook of psychotherapy and behaviour change. New York: Wiley. Rozeboom, W. W. (1991). Hyball: A method for subspace-constrained factor rotation. Multivariate Behavioral Research, 26, 163 177. Spielberger, C. D., Gorsuch, R. L. & Lushene, R. (1970). Manual for State-Trait Anxiety Inventor),. Palo Alto, Califo: Consulting Psychologists Press. Spielberger, C. D., Gorsuch, R. L., Lushene, R., Vagg, P. R. & Jacobs, G. A. (1983). Manual.for the State-Trait Anxiety Inventory (Form Y). Palo Alto, Califo: Consulting Psychologists Press. Stavaraki, C. & Vargo, B. (1986). The relationship of anxiety and depression: A review of the literature. British Journal of Psychiatry, 149, 7-16. Steer, R. A., Rissmiller, D. J., Ranieri, W. F. & Beck, A. T. (1993). Structure of the computer-assisted Beck Anxiety Inventory with psychiatric inpatients. Journal of Personality Assessment, 60, 532 542. Tanaka-Matsumi, J. & Kameoka, V. A. (1986). Reliabilities and concurrent validities of popular self report measures of depression, anxiety and social desirability. Journal of Consulting and Clinical Psychology, 54, 328 333. Tucker, L. R. & Lewis, C. (1973). The reliability coefficient for maximum likelihood factor analysis. Psychometrika, 38, 1 10. Zung, W. (1971). A rating instrument for anxiety disorders. Psychosomatics, 12, 371 379.