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Predicting criminal recidivism of insanity acquittees
lnternatmal Journal of Law and Psychlarry. PrInted I” the U.S.A. All rlghts reserved
Vol 11, 105-l
12.
1988 Copyright
0160.2527166 $3 00 + .OO C 1966 Pergamon P’less pt
Predicting Criminal Recidivism of Insanity Acquittees Stephen L. Bieber,* Richard A. Pasewark,** Katherine Bosten,*** and Henry J. Sfeadman****
At a time when the public media, legislators, and professionals express intense concern regarding the subsequent antisocial behavior of persons adjudicated insane, it is surprising that few studies exist that address this problem. Of these, some report a relatively high rate of criminal recidivism following the insanity adjudication. Others report a low rate. In a follow-up study of 44 Missouri acquittees, Morrow and Peterson (1966) found that 37% had been convicted of at least one felony 3 years subsequent to hospital discharge. This rate was comparable to the 35% recidivism found for a federal prison sample. All new offenses were serious enough to be classified as felonies. Most recidivists were found to repeat their original offense. The new offenses included assaults, child molestations, and “economic” offenses. Spodak, Silver, & Wright (1984) in a report upon 86 males adjudicated “not guilty by reason of insanity” (NGRI) and hospitalized in Maryland from August, 1967-June, 1976, and followed until mid 1982, noted that 48 (56%) experienced a subsequent arrest. Of 130 arrests, 47% resulted in convictions. The actual number of subjects convicted is not reported. Only the charges leading to conviction were reported, which included both misdemeanor’s (e.g., disorderly conduct, breaking and entering) and felonies (e.g., assault, rape, burglary, murder). In New York, Pasewark and associates conducted two studies that compared posthospitalization arrests of insanity acquittees with those of felons who had pled guilty to the same criminal charge and were imprisoned. The initial study (Pantle, Pasewark, & Steadman, 1980) comprised 46 individuals found insane from 1965-1971 and matched felons. During this period, acquittees were hospitalized in a facility administered by the Department of Corrections. At the time of study termination in 1976, 30 male and 4 female acquittees had been discharged from hospital. Nine (24%) had incurred a total of 30 posthospitalization arrests. Most of these arrests were for felonies, such as assault, rape, robbery, and murder. Of the 37 matched felons who had been released from imprisonment, 10 (27%) incurred 15 subsequent arrests. All arrestees in both *Associate 8207
Professor,
Departments
of Statistics
and Psychology,
University
of Wyoming,
Laramie,
WY
I, USA
**Professor, Department of Psychology, University of Wyoming, Laramie, WY 82071, USA ***Graduate Student, Department of Psychology, University of Wyoming, Laramie, WY 82071, USA ****Chief, Bureau of Survey and Education Research, Office of Mental Health, Albany, NY 12229, USA 105
106
S. L. BIEBER.
R. A. PASEWARK,
K. BOSTEN,
H. J. STEADMAN
groups were males. In the second investigation (Pasewark, Pantle, & Steadman, 1982), subjects had been institutionalized during 1971-1973. In this time period, NGRI acquittees were mandatorily hospitalized at civil facilities. By 1976, comparable arrest rates were obtained for the acquittee and felon groups. Similar results were also obtained in a parallel study in Connecticut (Phillips & Pasewark, 1980). In contrast to these reports which indicate a high recidivism rate for NCR1 acquittees, Canada and Oregon report a relatively low rate. Unfortunately, the Canadian study (Quinsey, Preusse, & Fernley, 1975) is not a “pure” insanity acquittal group, but also includes a number of defendants found “unfit to stand trial.” Of 56 persons discharged, only 3 were rearrested. This low rearrest rate is perhaps due to the lengthy hospitalization period of acquittees, averaging 8 years. Upon discharge, subjects were probably older and hence at lower risk for criminal behavior. The follow-up study by Bloom, Rogers, & Manson (1982) in Oregon is of particular interest in that it presents outcome information on an innovative mechanism, the Psychiatric Security Review Board, established statutorily in 1978. The Board is composed of a psychiatrist, a psychologist, a lawyer, a “person familiar with parole and probation, and a lay citizen” (Rogers & Bloom, 1982, p. 155). Upon NCR1 adjudication, the individual is committed to the care of the Board. Thenceforth, the Board assumes responsibility for the treatment and management of the person. In executing this charge, the Board has authority to contract with various facilities and agencies. Subjects in the Oregon study were 36 acquittees granted conditional release following trial and 90 granted conditional release following hospitalization by the Board from 1978-1980. During this period, another 138 acquittees were not released conditionally. Of the 126 conditionally released subjects, 40 were returned to hospital for “some breach of the conditional release plan or for deterioration in their mental condition” (p. 11). Six were “charged with new crimes.” Two were charged with felonies and four for misdemeanors. All charges were eventually dismissed. On the one hand, the Oregon data might, as the authors suggest, attest to the success of the Psychiatric Security Review Board by indicating a relatively low criminal recidivism rate. On the other hand, the data prove difficult to evaluate. First, the cut-off date of the follow-up period is not provided nor is the average release time of subjects given. Even if the follow up had been to the time of paper presentation in 1982, this period represents a much shorter one than that generally reported in other studies. Second, criminal recidivism is given in terms of “crimes charged,” without explanation of this term. However, it might very well mean that action preceded past the arrest stage to indictment of arraignment. If this is the case, it would represent something quite different than that denoted by arrest. Methods The initial subject pool comprised all 225 criminal defendants adjudicated NGRI in New York State during the period September 1, 1971-June 30, 1976. In accordance with statute, following the NCR1 adjudication, these persons
PREDICTING
RECIDIVISM
107
were hospitalized civilly until no longer dangerous. By August 3 1, 1981, 132 of the 225 acquittees had been discharged and 14 were on escape status. Of those discharged, 110 were males and 22 females. All 14 escapees were males. Utilizing stepwise discriminant procedures (Nie, Hull, Jenkins, Steinbrenner, & Bent, 1975) an attempt was made to predict posthospital recidivism, as measured by arrest, of the 132 released acquittees (i.e., to predict whether or not they incurred post hospital/arrests). Originally it was planned to predict membership in three posthospitalization groups: subjects having no arrests following hospital release; subjects having only misdemeanor arrests; and subjects having at least one felony arrest. The arrest characterization of these latter two groups indicated that 13 of the 28 felony subjects had committed crimes against people (e.g., murder, assault, robbery, and rape), and the other 15 primarily committed crimes against property (e.g., burglary, larceny, and arson); and 3 of the 9 misdemeanor subjects had committed crimes against persons (e.g., assault and sexual abuse). The limited size of the misdemeanor group, nine subjects, precluded the examination of this group separately; hence it was combined with the felony group. The two criterion groups were thus defined as: (1) those not incurring a subsequent arrest following hospital release; and (2) those experiencing a posthospitalization arrest. In many ways, discriminant analysis is similar to one-way analysis of variance in which several dependent variables exist simultaneously. However, instead of asking the manner in which variables change in relationship to group membership, the focus of interest in discriminant analysis is how group membership can be ascertained on the basis of the variables employed. In discriminant analysis, one could almost consider the variables as independent variates and groups as the dependent variate. Thus, discriminant analysis can be conceptualized as an attempt to identify the distinguishing characteristics of the groups on the basis of the variables employed. Two analyses were performed. In the first analysis, the variables utilized were those available when the acquittee was hospitalized following the NGRI adjudication. In the second analysis, two additional variables, available at the time of hospital discharge, were also examined. These were number of days hospitalized and number of escapes from hospital. Specific variables examined were: (a) gender; (b) ethnicity; (c) years of education; (d) marital status; (e) age at time of insanity plea; (f) severity of offense for which defendant pled insane (e.g., felony “A”, felony “C”, misdemeanor, violation); (g) whether the NGRI offense was a homicide or not (coded 1 and 0 respectively); (h) psychotic or non-psychotic diagnosis upon admission (coded 1 and 0 respectively); (i) whether subjects had any type of prior arrest; (j) whether subjects had a prior felony arrest; (k) age at first arrest; (1) age at first felony arrest; (m) total number of pre-NCR1 arrests; and (n) Crime History Index. To compute this index, minimum sentences accorded each arrest were summed. In this, a violation through a misdemeanor contributed .25 years; class E felony, 4.1 years; D felony, 7.1 years; C felony, 15 years; B felony, 25 years; and A felony, 45 years. Additional variables considered were (0) average severity of each arrest (the Crime History Index divided by the number of arrests incurred by a subject); (p) street years (age of subject at time of the NGRI arrest minus all known institutionalized periods); (q) crime severity per year (Crime History
108
S. L. BIEBER, R. A. PASEWARK,
K. BOSTEN, H. J. STEADMAN
Index divided by street years); (r) number of previous imprisonments; (s) days in prison prior to the NGRI offense; (t) number of prior civil hospitalizations; (u) days of prior civil hospitalizations; (v) number of previous hospitalizations associated with a criminal charge; (w) number of escapes while hospitalized for the NCR1 offense; and (x) length of NCR1 hospitalization. Results Table 1 provides some of the general characteristics of the 132 insanity acquittees who were discharged from hospital. Table 2 presents the general preand post-arrest histories of the 132 subjects. From Table 2, it can be discerned that of the 132 discharged acquittees, 38 (29%) incurred a posthospitalization arrest. Of the 77 NGRI acquittees who had no arrest prior to the NCR1 plea, only 13 (17%) had been arrested after discharge from hospital. Of the 55 subjects who had a prearrest, 25 (45%) had a postdischarge arrest. Table 3 presents the results in predicting group membership using those variables available at the time of the NCR1 hospitalization (i.e., all variables except length of hospitalization and number of escapes). An overall correct classification rate of 76.52% was achieved. From Table 3, it is apparent that the discriminant analysis procedure is most effective in predicting individuals who will not commit post hospitalization crimes. In this, the procedure correctly classified 81 (86.2%) of this group. Nevertheless, of the 94 subjects who did not incur a posthospitalization arrest, 13 (13.8%) had been predicted to do so. Much more difficulty is experienced in predicting those individuals who will commit a crime subsequent to hospital discharge. Of the 38 individuals experiencing a posthospita1 arrest, the discriminant analysis procedure falsely categorizes 18 (47.4%) into the no post arrest group. The chance level of correct classification for the post crime and no post crime groups was 28.8% and 71.2% respectively. Table 4 presents the discriminant structure coefficients of those variables most contributory to the discriminant function. These coefficients reflect the correlation between a specific variable and the discriminant function and are typically used for interpretation. From Table 4, it is seen that most efficacious in the prediction process are: number of prearrests (.68); severity of arrests per year (.61); a psychotic diagnosis (.58); an NCR1 offense of homicide (.51); fewer street years (- .30); and average prearrest severity (.27). These relationships differentiate those individuals who after release from hospitalization will commit post-NCR1 offenses from those who have not as yet committed any offense, as having more pre-NGRI arrests, committing more serious pre-NGRI crimes, more likely to be diagnosed as psychotic and having committed a homicide as their NGRI offense, and being “on the street” for relatively fewer years. This result was found to be statistically significant at the .OOOI level (xZ = 29.23, with 6 degrees of freedom). Table 5 provides the classification results when the additional variables of length of hospitalization and number of hospital escapes is included in the discriminant analysis. Inclusion of hospitalization length did not contribute significantly to the discriminant function. The contribution from the variable “number of escapes” increased the overall correct classification from 76.52% to 79.55%. This variable does nothing to increase the prediction rate of individu-
PREDICTING
RECIDIVISM
109
TABLE 1 Characteristics of Insanity Acquittees Discharged From Hospital Post-Arrest
Variable
N
Total
No Post-Arrest
N
010
N
92 8
75 19
79 21
110 22
83 17
100
94
100
132
100
O/O
O/O
Gender Male Female
35 3
Total
%
AS Under 21 21-36 31-40 41-50 Over 50
6 19 9 0 4
15 50 24 0 11
7 37 28 12 10
7 39 30 13 11
13 56 37 12 14
10 42 -28 9 11
Total
38
100
94
100
132
100
White Black Other Unknown
12 25 1 0
32 66 2 0
21 65 5 3
22 69 6 3
33 90 6 3
25 68 05 02
Total
38
100
94
100
132
100
13 25
34 66
58
62 38
71 61
54 46
3s
100
100
132
100
22
58 42
28 72
48 84
36 64
100
132
100
11 89
22 110
17 83
100
132
Ethnic
Homicide Yes No Total
x! 94
Psychosis Yes No Total
Is 38
100
12 26
32 68
38
100
26 ss 94
Escapes Yes No Total
10 s4 94
100
-
als who will not commit crimes. However, it does enhance identification of those who do engage in posthospitalization crime. Thus, of the 38 acquittees who experience posthospitalization arrest, 24 (63.2%) are correctly identified although 14 (36.8%) are incorrectly included in the predicted arrest-absent group. In contrast, when the number of escapes variable was not employed, the respective figures were 52.6% and 47.4%. Table 6 provides the results of this second discriminant analysis. From Table 6, the influence of including escapes is observed through its structure coefficient of .42. The addition of this variable does not change the basic nature of
110
S. L. BIEBER. R. A. PASEWARK,
K. BOSTEN,
H. J. STEADMAN
TABLE 2 Pre- and Post-Hospitalization Arrests of Insanity Acquittees Post-Arrest
Yes Pre-Arrest
N
Yes
25
No
13
No N
o/o
(19)
30
(10)
64
(23) (48)
010
TABLE 3 Classification Results Using the Variables Available at NGRI Adjudication
Predicted Actual Group Membership No Post-Arrest Post-Arrest Overall correct classification
Group Membership
No Post-Arrest
Post-Arrest
81 (86.2%) 18 (47.4%) 76.52%
13 (13.8%) 20 (52.6%)
the differentiating relationship detailed above, but does indicate that for those individuals who escape during their NGRI hospitalization there is a corresponding increase in the probability of their committing a post-NCR1 offense. Discussion In addition to the major thrust of the investigation in predicting criminal recidivism, the present investigation provides one of the longer follow-up studies of NGRI acquittees with respect to subsequent arrest. Generally, results prove discouraging. Of the 132 discharged acquittees, 38 (29%) had incurred arrests suggesting that current treatment methods for this group do little to TABLE 4 Discriminant Analysis Results Using the Variables Available at NGRI Adjudication
Variable Number of Pre-Arrests Average Severity per Year Psychotic Diagnosis Homicide at NGRI Average Pre-Arrest Severity Street Years
Discriminant Coefficient .68 .61 .58 .51 .27 -.30
111
PREDICTING RECIDIVISM
TABLE 5 Classification Results Using the Variables Available at Hospital Release Predicted Actual Group Membership No Post-Arrest Post-Arrest Overall correct classification
Group Membership
No Post-Arrest
Post-Arrest
81 (86.2%) 14 (36.8%) 79.55%
13 (13.8%) 24 (63.2%)
TABLE 6 Discriminant Analysis Results Using the Variables Available at Hospital Release Discriminant Coefficient
Variable Number of Pre-Arrests Average Severity per Year Psychotic Diagnosis Homicide at NGRI Number of Escapes Average Pre-Arrest Severity Street Years
.62 .56 53 .46 .42 .24 - .23
eliminate their antisocial behavior. The posthospitalization arrest histories of the discharged group are particularly disheartening when compared with the 14 individuals who had escaped from hospital and were not reapprehended at the time of study completion. These individuals were not included in the present study as they had not been discharged from hospital but remained on escape status. Of these escapees, 3 (21 o/o) had incurred arrests and 11 (79%) have not been subsequently arrested. Those who escape from hospital have lower arrest rates than those who are released through normal discharge procedures. The reported investigation represents the first in the literature that attempts to predict arrests of NGRI acquittees subsequent to mandatory hospitalization. If it can be gratuitously assumed that hospital discharge implies a staff prediction that acquittees will desist in antisocial behavior (i.e., are no longer dangerous), then the endeavor to predict subsequent criminal recidivism by non-clinical statistical means is mildly encouraging. Although hospital staff had a 29% incorrect prediction, (i.e., discharges who are arrested following hospitalization), utilization of the variables employed resulted in only a 20% misidentification. References Bloom,
J. D., Rogers,
J. L.. & Manson,
condirional
release and hospifalizafion.
Psychiatry,
Quebec
City, Canada.
S. M. (1982). After Oregon’s insanity defense: A comparison of Paper presented at the Eighth International Congress on Law and
112
S. L. BIEBER,
R. A. PASEWARK,
K. BOSTEN, H. J. STEADMAN
Morrow, W. R., 81 Peterson, D. B. (1966). Follow-up of discharged offenders-“not guilty by reason of insanity” and “criminal sexual psychopaths.” Journal of Criminal Lnw, Criminology and Police Science, 57,31-34. Nie, N. H., Hull, C. H., Jenkins, J. G., Steinbrenner, K., & Bent D. (1975). Slatrsficalfackagefor fhe Social Sciences (2nd ed.). New York: McGraw Hill. Pantle, M. L., Pasewark. R. A., & Steadman. H. J. (1980). Comparing institutionalization periods and subsequent arrests of insanity acquittees and convicted felons. JournulofPsychiafry and Law: 8. 305-316. Pasewark, R. A., Pantle, M. L., & Steadman, H. J. (1982). Detention and rearrest rates of persons found not guilty by reason of insanity and convicted felons. American Journal of Psychiatry, 139, 892-897. Phillips, B. L., & Pasewark, R. A. (1980). Insanity plea in Connecticut. Bullerin of the American Academy of
Psychiatry and the Law, 8, 335-344. Quinsey, V. L., Preusse, M., & Fernley, R. A. (1975). A follow-up of patients found “unfit to stand trial” or “not guilty because of insanity”. Canadian Psychiarric Association Journal, 20, 461-467. Rogers, J. L., & Bloom, J. D. (1982). Characteristics of persons committed to Oregon’s Psychiatric Security Review Board. Bullerin of rhe Amerrcan Academy of Psychiarry and the faw, IO, I55- 164. Spodak, M. K.. Silver, S. B., & Wright, C. V. (1984). Criminality of discharged insanity acquittees: Fifteen year experience in Maryland reviewed. Bulletin of the American Academy of Psychiatry and the Low, 12,
373-382.
Vol 11, 105-l
12.
1988 Copyright
0160.2527166 $3 00 + .OO C 1966 Pergamon P’less pt
Predicting Criminal Recidivism of Insanity Acquittees Stephen L. Bieber,* Richard A. Pasewark,** Katherine Bosten,*** and Henry J. Sfeadman****
At a time when the public media, legislators, and professionals express intense concern regarding the subsequent antisocial behavior of persons adjudicated insane, it is surprising that few studies exist that address this problem. Of these, some report a relatively high rate of criminal recidivism following the insanity adjudication. Others report a low rate. In a follow-up study of 44 Missouri acquittees, Morrow and Peterson (1966) found that 37% had been convicted of at least one felony 3 years subsequent to hospital discharge. This rate was comparable to the 35% recidivism found for a federal prison sample. All new offenses were serious enough to be classified as felonies. Most recidivists were found to repeat their original offense. The new offenses included assaults, child molestations, and “economic” offenses. Spodak, Silver, & Wright (1984) in a report upon 86 males adjudicated “not guilty by reason of insanity” (NGRI) and hospitalized in Maryland from August, 1967-June, 1976, and followed until mid 1982, noted that 48 (56%) experienced a subsequent arrest. Of 130 arrests, 47% resulted in convictions. The actual number of subjects convicted is not reported. Only the charges leading to conviction were reported, which included both misdemeanor’s (e.g., disorderly conduct, breaking and entering) and felonies (e.g., assault, rape, burglary, murder). In New York, Pasewark and associates conducted two studies that compared posthospitalization arrests of insanity acquittees with those of felons who had pled guilty to the same criminal charge and were imprisoned. The initial study (Pantle, Pasewark, & Steadman, 1980) comprised 46 individuals found insane from 1965-1971 and matched felons. During this period, acquittees were hospitalized in a facility administered by the Department of Corrections. At the time of study termination in 1976, 30 male and 4 female acquittees had been discharged from hospital. Nine (24%) had incurred a total of 30 posthospitalization arrests. Most of these arrests were for felonies, such as assault, rape, robbery, and murder. Of the 37 matched felons who had been released from imprisonment, 10 (27%) incurred 15 subsequent arrests. All arrestees in both *Associate 8207
Professor,
Departments
of Statistics
and Psychology,
University
of Wyoming,
Laramie,
WY
I, USA
**Professor, Department of Psychology, University of Wyoming, Laramie, WY 82071, USA ***Graduate Student, Department of Psychology, University of Wyoming, Laramie, WY 82071, USA ****Chief, Bureau of Survey and Education Research, Office of Mental Health, Albany, NY 12229, USA 105
106
S. L. BIEBER.
R. A. PASEWARK,
K. BOSTEN,
H. J. STEADMAN
groups were males. In the second investigation (Pasewark, Pantle, & Steadman, 1982), subjects had been institutionalized during 1971-1973. In this time period, NGRI acquittees were mandatorily hospitalized at civil facilities. By 1976, comparable arrest rates were obtained for the acquittee and felon groups. Similar results were also obtained in a parallel study in Connecticut (Phillips & Pasewark, 1980). In contrast to these reports which indicate a high recidivism rate for NCR1 acquittees, Canada and Oregon report a relatively low rate. Unfortunately, the Canadian study (Quinsey, Preusse, & Fernley, 1975) is not a “pure” insanity acquittal group, but also includes a number of defendants found “unfit to stand trial.” Of 56 persons discharged, only 3 were rearrested. This low rearrest rate is perhaps due to the lengthy hospitalization period of acquittees, averaging 8 years. Upon discharge, subjects were probably older and hence at lower risk for criminal behavior. The follow-up study by Bloom, Rogers, & Manson (1982) in Oregon is of particular interest in that it presents outcome information on an innovative mechanism, the Psychiatric Security Review Board, established statutorily in 1978. The Board is composed of a psychiatrist, a psychologist, a lawyer, a “person familiar with parole and probation, and a lay citizen” (Rogers & Bloom, 1982, p. 155). Upon NCR1 adjudication, the individual is committed to the care of the Board. Thenceforth, the Board assumes responsibility for the treatment and management of the person. In executing this charge, the Board has authority to contract with various facilities and agencies. Subjects in the Oregon study were 36 acquittees granted conditional release following trial and 90 granted conditional release following hospitalization by the Board from 1978-1980. During this period, another 138 acquittees were not released conditionally. Of the 126 conditionally released subjects, 40 were returned to hospital for “some breach of the conditional release plan or for deterioration in their mental condition” (p. 11). Six were “charged with new crimes.” Two were charged with felonies and four for misdemeanors. All charges were eventually dismissed. On the one hand, the Oregon data might, as the authors suggest, attest to the success of the Psychiatric Security Review Board by indicating a relatively low criminal recidivism rate. On the other hand, the data prove difficult to evaluate. First, the cut-off date of the follow-up period is not provided nor is the average release time of subjects given. Even if the follow up had been to the time of paper presentation in 1982, this period represents a much shorter one than that generally reported in other studies. Second, criminal recidivism is given in terms of “crimes charged,” without explanation of this term. However, it might very well mean that action preceded past the arrest stage to indictment of arraignment. If this is the case, it would represent something quite different than that denoted by arrest. Methods The initial subject pool comprised all 225 criminal defendants adjudicated NGRI in New York State during the period September 1, 1971-June 30, 1976. In accordance with statute, following the NCR1 adjudication, these persons
PREDICTING
RECIDIVISM
107
were hospitalized civilly until no longer dangerous. By August 3 1, 1981, 132 of the 225 acquittees had been discharged and 14 were on escape status. Of those discharged, 110 were males and 22 females. All 14 escapees were males. Utilizing stepwise discriminant procedures (Nie, Hull, Jenkins, Steinbrenner, & Bent, 1975) an attempt was made to predict posthospital recidivism, as measured by arrest, of the 132 released acquittees (i.e., to predict whether or not they incurred post hospital/arrests). Originally it was planned to predict membership in three posthospitalization groups: subjects having no arrests following hospital release; subjects having only misdemeanor arrests; and subjects having at least one felony arrest. The arrest characterization of these latter two groups indicated that 13 of the 28 felony subjects had committed crimes against people (e.g., murder, assault, robbery, and rape), and the other 15 primarily committed crimes against property (e.g., burglary, larceny, and arson); and 3 of the 9 misdemeanor subjects had committed crimes against persons (e.g., assault and sexual abuse). The limited size of the misdemeanor group, nine subjects, precluded the examination of this group separately; hence it was combined with the felony group. The two criterion groups were thus defined as: (1) those not incurring a subsequent arrest following hospital release; and (2) those experiencing a posthospitalization arrest. In many ways, discriminant analysis is similar to one-way analysis of variance in which several dependent variables exist simultaneously. However, instead of asking the manner in which variables change in relationship to group membership, the focus of interest in discriminant analysis is how group membership can be ascertained on the basis of the variables employed. In discriminant analysis, one could almost consider the variables as independent variates and groups as the dependent variate. Thus, discriminant analysis can be conceptualized as an attempt to identify the distinguishing characteristics of the groups on the basis of the variables employed. Two analyses were performed. In the first analysis, the variables utilized were those available when the acquittee was hospitalized following the NGRI adjudication. In the second analysis, two additional variables, available at the time of hospital discharge, were also examined. These were number of days hospitalized and number of escapes from hospital. Specific variables examined were: (a) gender; (b) ethnicity; (c) years of education; (d) marital status; (e) age at time of insanity plea; (f) severity of offense for which defendant pled insane (e.g., felony “A”, felony “C”, misdemeanor, violation); (g) whether the NGRI offense was a homicide or not (coded 1 and 0 respectively); (h) psychotic or non-psychotic diagnosis upon admission (coded 1 and 0 respectively); (i) whether subjects had any type of prior arrest; (j) whether subjects had a prior felony arrest; (k) age at first arrest; (1) age at first felony arrest; (m) total number of pre-NCR1 arrests; and (n) Crime History Index. To compute this index, minimum sentences accorded each arrest were summed. In this, a violation through a misdemeanor contributed .25 years; class E felony, 4.1 years; D felony, 7.1 years; C felony, 15 years; B felony, 25 years; and A felony, 45 years. Additional variables considered were (0) average severity of each arrest (the Crime History Index divided by the number of arrests incurred by a subject); (p) street years (age of subject at time of the NGRI arrest minus all known institutionalized periods); (q) crime severity per year (Crime History
108
S. L. BIEBER, R. A. PASEWARK,
K. BOSTEN, H. J. STEADMAN
Index divided by street years); (r) number of previous imprisonments; (s) days in prison prior to the NGRI offense; (t) number of prior civil hospitalizations; (u) days of prior civil hospitalizations; (v) number of previous hospitalizations associated with a criminal charge; (w) number of escapes while hospitalized for the NCR1 offense; and (x) length of NCR1 hospitalization. Results Table 1 provides some of the general characteristics of the 132 insanity acquittees who were discharged from hospital. Table 2 presents the general preand post-arrest histories of the 132 subjects. From Table 2, it can be discerned that of the 132 discharged acquittees, 38 (29%) incurred a posthospitalization arrest. Of the 77 NGRI acquittees who had no arrest prior to the NCR1 plea, only 13 (17%) had been arrested after discharge from hospital. Of the 55 subjects who had a prearrest, 25 (45%) had a postdischarge arrest. Table 3 presents the results in predicting group membership using those variables available at the time of the NCR1 hospitalization (i.e., all variables except length of hospitalization and number of escapes). An overall correct classification rate of 76.52% was achieved. From Table 3, it is apparent that the discriminant analysis procedure is most effective in predicting individuals who will not commit post hospitalization crimes. In this, the procedure correctly classified 81 (86.2%) of this group. Nevertheless, of the 94 subjects who did not incur a posthospitalization arrest, 13 (13.8%) had been predicted to do so. Much more difficulty is experienced in predicting those individuals who will commit a crime subsequent to hospital discharge. Of the 38 individuals experiencing a posthospita1 arrest, the discriminant analysis procedure falsely categorizes 18 (47.4%) into the no post arrest group. The chance level of correct classification for the post crime and no post crime groups was 28.8% and 71.2% respectively. Table 4 presents the discriminant structure coefficients of those variables most contributory to the discriminant function. These coefficients reflect the correlation between a specific variable and the discriminant function and are typically used for interpretation. From Table 4, it is seen that most efficacious in the prediction process are: number of prearrests (.68); severity of arrests per year (.61); a psychotic diagnosis (.58); an NCR1 offense of homicide (.51); fewer street years (- .30); and average prearrest severity (.27). These relationships differentiate those individuals who after release from hospitalization will commit post-NCR1 offenses from those who have not as yet committed any offense, as having more pre-NGRI arrests, committing more serious pre-NGRI crimes, more likely to be diagnosed as psychotic and having committed a homicide as their NGRI offense, and being “on the street” for relatively fewer years. This result was found to be statistically significant at the .OOOI level (xZ = 29.23, with 6 degrees of freedom). Table 5 provides the classification results when the additional variables of length of hospitalization and number of hospital escapes is included in the discriminant analysis. Inclusion of hospitalization length did not contribute significantly to the discriminant function. The contribution from the variable “number of escapes” increased the overall correct classification from 76.52% to 79.55%. This variable does nothing to increase the prediction rate of individu-
PREDICTING
RECIDIVISM
109
TABLE 1 Characteristics of Insanity Acquittees Discharged From Hospital Post-Arrest
Variable
N
Total
No Post-Arrest
N
010
N
92 8
75 19
79 21
110 22
83 17
100
94
100
132
100
O/O
O/O
Gender Male Female
35 3
Total
%
AS Under 21 21-36 31-40 41-50 Over 50
6 19 9 0 4
15 50 24 0 11
7 37 28 12 10
7 39 30 13 11
13 56 37 12 14
10 42 -28 9 11
Total
38
100
94
100
132
100
White Black Other Unknown
12 25 1 0
32 66 2 0
21 65 5 3
22 69 6 3
33 90 6 3
25 68 05 02
Total
38
100
94
100
132
100
13 25
34 66
58
62 38
71 61
54 46
3s
100
100
132
100
22
58 42
28 72
48 84
36 64
100
132
100
11 89
22 110
17 83
100
132
Ethnic
Homicide Yes No Total
x! 94
Psychosis Yes No Total
Is 38
100
12 26
32 68
38
100
26 ss 94
Escapes Yes No Total
10 s4 94
100
-
als who will not commit crimes. However, it does enhance identification of those who do engage in posthospitalization crime. Thus, of the 38 acquittees who experience posthospitalization arrest, 24 (63.2%) are correctly identified although 14 (36.8%) are incorrectly included in the predicted arrest-absent group. In contrast, when the number of escapes variable was not employed, the respective figures were 52.6% and 47.4%. Table 6 provides the results of this second discriminant analysis. From Table 6, the influence of including escapes is observed through its structure coefficient of .42. The addition of this variable does not change the basic nature of
110
S. L. BIEBER. R. A. PASEWARK,
K. BOSTEN,
H. J. STEADMAN
TABLE 2 Pre- and Post-Hospitalization Arrests of Insanity Acquittees Post-Arrest
Yes Pre-Arrest
N
Yes
25
No
13
No N
o/o
(19)
30
(10)
64
(23) (48)
010
TABLE 3 Classification Results Using the Variables Available at NGRI Adjudication
Predicted Actual Group Membership No Post-Arrest Post-Arrest Overall correct classification
Group Membership
No Post-Arrest
Post-Arrest
81 (86.2%) 18 (47.4%) 76.52%
13 (13.8%) 20 (52.6%)
the differentiating relationship detailed above, but does indicate that for those individuals who escape during their NGRI hospitalization there is a corresponding increase in the probability of their committing a post-NCR1 offense. Discussion In addition to the major thrust of the investigation in predicting criminal recidivism, the present investigation provides one of the longer follow-up studies of NGRI acquittees with respect to subsequent arrest. Generally, results prove discouraging. Of the 132 discharged acquittees, 38 (29%) had incurred arrests suggesting that current treatment methods for this group do little to TABLE 4 Discriminant Analysis Results Using the Variables Available at NGRI Adjudication
Variable Number of Pre-Arrests Average Severity per Year Psychotic Diagnosis Homicide at NGRI Average Pre-Arrest Severity Street Years
Discriminant Coefficient .68 .61 .58 .51 .27 -.30
111
PREDICTING RECIDIVISM
TABLE 5 Classification Results Using the Variables Available at Hospital Release Predicted Actual Group Membership No Post-Arrest Post-Arrest Overall correct classification
Group Membership
No Post-Arrest
Post-Arrest
81 (86.2%) 14 (36.8%) 79.55%
13 (13.8%) 24 (63.2%)
TABLE 6 Discriminant Analysis Results Using the Variables Available at Hospital Release Discriminant Coefficient
Variable Number of Pre-Arrests Average Severity per Year Psychotic Diagnosis Homicide at NGRI Number of Escapes Average Pre-Arrest Severity Street Years
.62 .56 53 .46 .42 .24 - .23
eliminate their antisocial behavior. The posthospitalization arrest histories of the discharged group are particularly disheartening when compared with the 14 individuals who had escaped from hospital and were not reapprehended at the time of study completion. These individuals were not included in the present study as they had not been discharged from hospital but remained on escape status. Of these escapees, 3 (21 o/o) had incurred arrests and 11 (79%) have not been subsequently arrested. Those who escape from hospital have lower arrest rates than those who are released through normal discharge procedures. The reported investigation represents the first in the literature that attempts to predict arrests of NGRI acquittees subsequent to mandatory hospitalization. If it can be gratuitously assumed that hospital discharge implies a staff prediction that acquittees will desist in antisocial behavior (i.e., are no longer dangerous), then the endeavor to predict subsequent criminal recidivism by non-clinical statistical means is mildly encouraging. Although hospital staff had a 29% incorrect prediction, (i.e., discharges who are arrested following hospitalization), utilization of the variables employed resulted in only a 20% misidentification. References Bloom,
J. D., Rogers,
J. L.. & Manson,
condirional
release and hospifalizafion.
Psychiatry,
Quebec
City, Canada.
S. M. (1982). After Oregon’s insanity defense: A comparison of Paper presented at the Eighth International Congress on Law and
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R. A. PASEWARK,
K. BOSTEN, H. J. STEADMAN
Morrow, W. R., 81 Peterson, D. B. (1966). Follow-up of discharged offenders-“not guilty by reason of insanity” and “criminal sexual psychopaths.” Journal of Criminal Lnw, Criminology and Police Science, 57,31-34. Nie, N. H., Hull, C. H., Jenkins, J. G., Steinbrenner, K., & Bent D. (1975). Slatrsficalfackagefor fhe Social Sciences (2nd ed.). New York: McGraw Hill. Pantle, M. L., Pasewark. R. A., & Steadman. H. J. (1980). Comparing institutionalization periods and subsequent arrests of insanity acquittees and convicted felons. JournulofPsychiafry and Law: 8. 305-316. Pasewark, R. A., Pantle, M. L., & Steadman, H. J. (1982). Detention and rearrest rates of persons found not guilty by reason of insanity and convicted felons. American Journal of Psychiatry, 139, 892-897. Phillips, B. L., & Pasewark, R. A. (1980). Insanity plea in Connecticut. Bullerin of the American Academy of
Psychiatry and the Law, 8, 335-344. Quinsey, V. L., Preusse, M., & Fernley, R. A. (1975). A follow-up of patients found “unfit to stand trial” or “not guilty because of insanity”. Canadian Psychiarric Association Journal, 20, 461-467. Rogers, J. L., & Bloom, J. D. (1982). Characteristics of persons committed to Oregon’s Psychiatric Security Review Board. Bullerin of rhe Amerrcan Academy of Psychiarry and the faw, IO, I55- 164. Spodak, M. K.. Silver, S. B., & Wright, C. V. (1984). Criminality of discharged insanity acquittees: Fifteen year experience in Maryland reviewed. Bulletin of the American Academy of Psychiatry and the Low, 12,
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