Scaling of life change: Comparison of direct and indirect methods

Journal of Psychosomatic Research, Vol. 15, pp. 221 to 227. Pergamon Press, 1971. Printed in Northern Ireland

SCALING OF LIFE CHANGE: COMPARISON OF DIRECT AND INDIRECT LIBBY 0.

RUCHt

METHODS*

and THOMAS H. HOLMES

(Received 31 July 1970) PREVIOUS studies [l-7] have shown that a cluster of life events requiring change in the individual’s accustomed way of life are significantly associated with the onset of disease. Holmes and Rahe [3] have developed a method for the quantification of the amount of change associated with these life events. Subjects were asked to judge the amount of social readjustment necessitated by 43 life events taken from medical case histories which reflect changes in such areas as family structure, occupation, income, education, health, and peer relationships. One of the life event items was arbitrarily valued at 500 and the subjects rated the remaining items numerically in proportion to this value. The life events were then arranged in rank order of magnitude. A high agreement was found among the subjects on the rating of the relative severity of the social readjustment necessitated by the various life events. This finding was supported by follow-up studies [8-121 which revealed an essential agreement with the American sample despite some cultural differences. The first purpose of the present study was to replicate the study of Holmes and Rahe [3] using a different sample to test further the degree of value consensus concerning the amount of change involved in the various life events [13]. A younger sample was selected to determine if age influenced how individuals perceive the magnitude of change associated with life events. It was assumed that as late adolescents have usually not actually experienced many of these life changes, their evaluations of them may be different. Moreover, sociological literature [ 14-161 suggests that adolescents are not only different from adults in being relatively inexperienced but also that they participate in a distinct subculture with its own norms and values. In addition, the adolescent world has its particular challenges, anxieties, and opportunities. If the late adolescent group scales the life events differently from the adult group, then a pervasive value consensus can be questioned; if the items are scaled similarly by both samples, then weight is added to the conclusions drawn by Holmes and Rahe. The second purpose of this study is the comparison of two scaling methods, magnitude estimation and paired comparisons, used to measure the perceived amount of change associated with the social phenomena [13]. The method of magnitude estimation used by Holmes and Rahe is a relatively new scaling device in the field of sociology and so was supplemented by Thurstone’s method of paired comparisons [17], which has different theoretical assumptions and has been widely applied in sociological research. In paired comparisons, each stimulus is paired and compared with every other stimulus so that each stimulus functions as a standard. Thus, subjects are asked to decide whether marriage or divorce involves the greater amount of life change. With the magnitude estimation method, one stimulus is arbitrarily given a

+ From the Department of Psychiatry, University of Washington School of Medicine, Seattle, Washington, 98105. j’ Present address is Department of Sociology, Stanford University, Stanford, California 94305, U.S.A. 221

222

L. 0. RUCH and T. H. HOLMES

numerical value and the subjects rate the other events numerically in proportion to this value. For example, if the amount of life change associated with marriage is set at 500, the subject is asked to compare divorce with marriage and give divorce a proportional number. A previous experiment by Stevens [18] found that the direct (magnitude estimation) and indirect (paired comparisons) measurement devices generated different results when used to scale identical stimuli, and, furthermore, that the resultant scales were mathematically related regardless of the physical variable scaled : The Thurstonian paired comparisons scale was a logarithmic function of the Stevens magnitude estimation scale. In summary, the purposes of this replication are (1) to compare the adolescent sample with the adult sample of Holmes and Rahe, and (2) to compare the scaling methods of magnitude estimation and paired comparisons. METHODS

AND

PROCEDURES

The subjects

Table 1 shows the distribution of the total adult and adolescent samples with respect to age, education, class, ethnicity, generation, and religion. The sample of 394 adult individuals used by Holmes and Rahe [3] was a sample of convenience. The late adolescent sample of 211 used in this study was selected to test the hypothesis of a uniform value consensus and so differs from the Holmes and Rahe sample in respect to age. 52 per cent of the adult sample were between 21 and 30 yr old and 48 per cent were 30 yr old or more. Although slightly more than half of the adult sample was under 30, the youngest were medical students in their middle twenties. The adolescent sample was composed of college students who were all under 30 with a mean age of 18 yr. While the age differences were of primary concern in this study, the adolescent group also differed from the adult group in respect to ethnicity and religion due to the greater proportion of Orientals in the adolescent sample. However, as the scaling of life events by adults in America and Japan [8] was not significantly affected by ethnicity and religion, it is assumed that these variables did not affect the results of this study as well. The scaling methods Magnitude estimation. The Social Readjustment Rating Questionnaire was administered to the late adolescent group. The instructions and items have been previously described [3]. Each respondent gave a number to each item (life event) expressing the amount of life change involved. The total sum for the item was calculated, and the mean number divided by 10 gave a scale score for that item, thus generating a scale of the life events in terms of the intensity and duration of social readjustment. Paired comparisons. With this method, each item was paired with every other one, one member of the pair was judged more severe than the other. The original 43 life events were reduced to 11 representative items to make the computation less unwieldly and were randomized to reduce rater fatigue. The 11 items made 55 pairs. Subjects were asked to compare and underline the member of each pair judged more serious for the average person. In computing the paired comnarison scale scores. the Thurstone method of paired comparisons (Case V) was used [19]. First, a frequency table was calculated showing the number of times each item was chosen as more serious over every other item, followed by a proportion matrix specifying in what proportion the item was selected. Then the proportions were translated into a normal deviate matrix, and the scale scores were derived from computing the difference between the means of the normal deviates.

RESULTS Comparison

of adolescent

and adult samples

Table 2 compares the item scale scores (arithmetic means) and their rankings for the adult and adolescent groups. The t%lings indicate a high agreement between the adult and adolescent samples concerning the amount of social readjustment involved in the 43 life events. The Spearman’s rank order correlation coefficient (r,) between the adult and adolescent groups is very high (0.97). The adolescent judges place about 25 per cent of the 43 items in exactly the same position as the adults and 80 per cent of the items within three places of their original position. The three

223

Scaling of life change TABLE

I.-DISTRIBUTION OF ADULT AND ADOLESCENT SAMPLES BY AGE, EDUCATION, CLASS, ETHNIC AFFILIATION, GENERATION, AND RELIGION

Age Education Class Ethnic affiliation

Generation Religion

Under 30 30-60 Over 60 Below college level College level or more Middle class Lower class Caucasian Oriental Negro Others First Second Third or more Protestant Catholic Buddhist Jewish Others Agnostic, atheist, or none

Adult

Adolescent

206 137 51 182 212 323 71 363 12 19 0 19 69 306 241 42 12 19 33 47 II=394

211 0 0 0 211 158 57 50 136 0 25 19 112 70 71 32 30 1 20 55 n=211

items which are ranked most differently by the two samples are sexual difficulties, mortgages or loans of less than $10,000, and revision of personal habits. The adolescent sample regarded sexual difficulties and mortgages as involving more change than did the adult group whereas they gave less weight to the revision of personal habits. Comparison

of magnitude

and paired comparisons

methods

Table 3 allows comparison of the rank order of the items and the scale scores for the adolescent group generated by the two different scaling methods (magnitude estimation and paired comparisons) and also comparison of the rank order of the items and the scale scores for the adolescent and the adult groups by magnitude estimation. Comparison of the direct (magnitude estimation) and indirect (paired comparisons) scale scores shows that the two measures yield quite similar results in the adolescent group. The Spearman’s rank order correlation coefficient (r,) between the scale scores is positive and very high (O-93). By both scaling methods, death of spouse is considered to produce the most change and minor law violations the least. On the other hand, marriage is ranked lower than divorce and death of close family member with the magnitude estimation method, whereas it is the second highest ranked with the paired comparisons method. The next three items, change in financial state, pregnancy, and retirement in the paired comparisons scale are ranked in reverse order on the magnitude estimation scale. Change in social activities is ranked higher than begin or end school in the paired comparisons scale whereas the reverse is true in the magnitude estimation scale. Thus the order of the paired comparisons varies from the rank order of the magnitude estimations in both the adult and adolescent groups, and the rank order of the magnitude estimations of the 11 life events is identical by both the adolescent and the adult groups. DISCUSSION

There is a high agreement between the adult and the adolescent samples on the seriousness of life events. The rank order correlation between the adult and adolescent groups of O-97 indicates a high consensus and supports the hypothesis of a general value agreement concerning the amount of change involved in the life events. Some of the life events are evaluated differently by the adolescents than by the adults, which suggests subcultural differences as well as a common value system. The three most variant items are revision of personal habits, taking on a mortgage of less than $10,000, and sexual difficulties. Evaluation of an event may depend in part on the

224

L. 0. TABLE

Z.-RANKING SAMPLE

ON

RUCH

and T. H.

HOLMES

AND ITEM SCALE SCORES OF THE TOTAL ADULT AND ADOLESCENT THE SOCIAL READJUSTMENT RATING QUESTIONNAIRE Adult

Life event

Rank of arithmetic mean value

Death of spouse Divorce Marital separation Jail term Death of a close family member Major personal injury or illness Marriage Fired from work Marital reconciliation Retirement Major change in health of family member Pregnancy Sex difficulties Gain of a new family member Business readjustment Change in financial state Death of a close friend Change to a different line of work Change in number of arguments with spouse Mortgage over $10,000 Foreclosure of mortgage or loan Change in responsibilities at work Son or daughter leaving home Trouble with in-laws Outstanding persona1 achievement Wife begins or stops work Begin or end school Change in living conditions Revision of personal habits Trouble with boss Change in work hours or conditions Change in residence Change in schools Change in recreation Change in church activities Change in social activities Mortgage or loan less than $10,000 Change in sleeping habits Change in number of family get-tog&hers Change in eating habits Vacation Christmas Minor violations of the law

1

2 4 6

7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

group Arithmetic mean value 100 73 65 63 63 53 50 47 45 45 44 40 39 39 39 38 37 36 35 31 30 29 29 29 28 26 26 25 24 23 20 20 20 19 19 18 17 16 15 15 13 12 11

Adolescent group Rank of arithmetic Arithmetic mean value mean value 1 2 3 8 4 6 9 7 10 11 16 13 5 17 15 14 12 21 19 18 23 20 25 22 28 27 26 24 35 33 29 30 34 36 38 32 31 41 37 40 39 42 43

69 60 55 50 54 50 50 50 47 46 44 45 51 43 44 44 46 35 41 41 36 38 34 36 31 32 34 35 26 26 30 28 26 26 21 28 28 18 22 18 19 16 12

value placed on its seriousness and also upon the individual’s amount of experience or familiarity with the event. Thus there are two pairs of dichotomies possible-an event can be ranked as high or low depending upon the presence or absence of experience. It may be that the adolescent group tends to rank revision of personal habits lower than the adult group because they are accustomed to this type of change from their educational experience whereas they rank taking out a mortgage of less than $10,000 and sexual difficulties higher than the adult sample because the relative lack of experience in these areas produces an overestimation of the social readjustment

Scaling of life change

225

TABLE 3.-RANKING AND SCALE SCORES OF THE TOTAL ADOLESCENT GROUP USING MAGNITUDE ESTIMATION AND PAIRED COMPARISONS SCALING METHODS AND RANKING AND SCALE SCORES OF THE TOTAL ADULT GROUP USING THE MAGNITUDE ESTIMATION METHOD

Adolescent Item Death of spouse Marriage Divorce Death of close family member Change in financial state Pregnancy Retirement Trouble with in-laws Change in social activities Begin or end school Minor law violations

Paired Rank order 1 2 3 4 5 6 7 8 9 10 11

Comparison Scale value 2.1685 1.7725 1.5954 1.4894 1.1259 1.0730 0.9860 0.9075 0.4789 03397 0~0000

Adult

Magnitude Rank order

estimation Scale value

Magnitude Rank order

estimation Scale value

1 4 2 3 7 6 5 8 10 9 11

69 50 60 54 44 45 46 36 28 34 12

1 4 2 3 7 6 5 8 10 9 11

100 50 73 63 38 40 45 29 36 26 11

required. Taking out a mortgage over $10,000 was also considered more serious by the adolescent than by the adult sample. On the other hand, it is also possible that adolescents would tend to rate sexual difficulties more highly as sexual identification is one of the crucial tasks of the adolescent years and so much interest and value are placed on sexual adjustment regardless of the particular individual’s experience. In summary, comparison of the scale scores of the items for the two groups suggests a broad value consensus concerning the estimation of change required by these life events with some variation due to subcultural norms and values. These findings support the hypothesis of a general value agreement on the significance of life events. Although Stevens’ experiment [ 181 found that direct and indirect scaling methods yielded consistently different results, in this study the magnitude estimation and paired comparison scaling methods yielded similar results in the adolescent group. The Spearman’s rank order correlation coefficient (rs) of 0.93 indicates a strong positive relationship between the results of the magnitude estimation and the paired comparisons methods. Galanter and Messick [20] found that the relationship between the magnitude estimation and paired comparisons scales was nonlinear and so used an antilog transformation to change Thurstone’s values to correct for nonlinearity. The paired comparisons and the magnitude estimations in this study correlate almost as highly (rs = 0.93) as do the magnitude estimations by the different groups (rs = 1.00 for 11 items and r, = O-97 for 43 items), and the relationship between the two scales is virtually linear when plotted (see Fig. 1). If the two methods had yielded very different results, one would question the possibility of scaling life events and the theoretical assumptions underlying the two methods. However, in this study this was not the case. The two methods scaled the life events so similarly that the relationship between the two scales appears linear. These results indicate that both the magnitude estimation and the paired comparisons methods are useful devices for scaling the social readjustment associated with life events. As the magnitude estimation method involves less statistical computation and can scale a relatively larger number of stimuli than the paired comparisons method, it is suggested that this direct scaling method developed in psychophysical research can be of considerable usefulness in sociological research.

L. 0. RUCH and T. H. HOLMES

226

2 400

l

2 200 c

/

2 ooo-

I 800-m : $

.

.

I 6C,3-

In

.

.??

i’

I400-

: @

IZOO-

.-:: L g E

IOCO-

E x .L

0600-

A! 0600-

0 400--

0.200

-

0

I IO’

20

30

Magnitude

FIG. l.-Linear

relation

40

estimation

100

60e

50

scale

scores

between the Magnitude Estimation Comparisons Scale.

Scale and the Paired

SUMMARY

The data the hypothesis analysis also comparisons) similar scales

from an adolescent sample compared with an adult sample supported of a general value consensus about the seriousness of life events. The revealed that the direct (magnitude estimation) and indirect (paired scaling methods, which are based on different assumptions, produced of life events when applied to the same sample.

Acknowledgement-The

authors

are indebted

to Minoru

Masuda,

Ph.D., for his helpful advice

and criticism. REFERENCES HAWKINS N. G., DAVIES R. and HOLMES T. H. Evidence of psychosocial factors in the development of pulmonary tuberculosis. Am. Rev. Taberc. Dis. 75, 5 (1957). RAHE R. H., MEYER M., SMITH M., KJAER G. and HOLMEST. H. Social stress and illness onset. J. Psychosom. Res. 8, 35 (1964). HOLMEST. H. and RAHE R. H. The social readjustment rating scale. J. Psychosom. Res. 11, 213 (1967).

RAHE R. H. Life crisis and health change. In Psychotroptic Drug Response: Advances in (Edited by MAY P. R. A. and WITTENBORNJ. R.), pp. 92-125. Charles C. Thomas, Springfield, Illinois (1969). 5. HOLMEST. S. and HOLMEST. H. Short-term intrusions into the life style routine. J. Psychosom. Prediction

Res. 14, 121 (1970).

6. HOLMEST. S. Adaptive behavior and health change. Medical Thesis, University of Washington, Seattle (1970). 7. WYLER A. R., MASUDA M. and HOLMEST. H. Magnitude of life events and seriousness of illness. Psychosom. Med. In press.

Scaling of life change

227

8. MASUDAM. and HOLMEST. H. The social readjustment rating scale: a cross-cultural study of Japanese and Americans. J. Psychosom. Res. 11, 227 (1967). 9. CELDRANH. H. The cross-cultural consistency of two social consensus scales: the seriousness of illness rating scale and the social readjustment rating scale in Spain. Medical Thesis, University of Washington, Seattle (1970). 10. HARMOND. K., MASUDAM. and Holmes T. H. The social readjustment rating scale: a crosscultural study of Western Europeans and Americans. J. Psychosom. Res. 14, 391 (1971). 11. KOMAROFFA. L., MASUDA M. and HOLMEST. H. The social readjustment rating scale: a comparative study of Negro, Mexican, and white Americans. J. Psychosom. Res. 12, 121 (1968). 12. RAHE R. H. Multi-cultural 13.

14. 15. 16. 17. 18. 19. 20.

correlations of life change scaling: America, Japan, Denmark and Sweden. J. Psychosom. Res. 13, 191 (1969). RUCH L. 0. Scaling of life stress with direct and indirect scaling methods. M. A. Thesis, University of Hawaii (1967). KENI~TON K. Social change and youth in America. In The Challenge of Youth (Edited by ERIKSONE. H.), Doubleday, New York (1963). ERIKSON E. H. (Editor) The ChaZIenge of Youth. Doubleday, New York (1963). PARSONST. Youth in the context of American society. In The Challenge of Youth (Edited by ERIKSON E. H.), Doubleday, New York (1963). TORGERSONW. S. Theory and Methods of Scaling. Wiley, New York (1958). STEVENSS. S. A metric for the social consensus: methods of sensory psychophysics have been used to aauae the intensity of ovinions and attitudes. Science 151, 532 (1966). THURST~NE-L. L. The Mtksurekent of Values. University of Chicago Press; Chicago (1959). GALANTERE. and MESSICKS. The relation between category and magnitude scales of loudness. Psychol. Rev. 68, 371 (1961).