DEMOGRAPHIC VARIABLES AND MMPI RESPONSES1 A. G . DEVRIES

University of Briliah Columbia, Vancower, Canada and Suicide Prevention Center, L a Angela, Californth

PROBLEM Although the MMPI has been used for purposes other than psychiatric classi-

fications, relatively little attention has been paid to the more common conventional demographic variables. Brower ( l ) found a negative correlation between intelligence and the Hysteria, Hypochondriasis and Psychopathic Deviate scales.

In contrast, Winfield (‘) found no significant correlations between intelligence and these scales. Nor was intelligence related to the Depressive scale. A small (.28 at the .01 1.s.) correlation was found between intelligence and the Masculinity- Femininity scale. Wexner (a) who also correlated intelligence with the MMPI scales only obtained a significant relationship between intelligence and the Paranoia scale. Brozek and Keysc2) found a relationship between age and responses to the “?”, the .“K”, the “F” and the Hypochondriasis scales.

These researchers seem to indicate that other common control variables may influence MMPI responses besides age and intelligence. This study investigated the influence of age, education, marital status, occupation, religion, number of hospital admissions, and psychiatric diagnosis on MMPI responses.

METHOD The short form MMPI was administered to 600 Caucasian male veteran neuro-

psychiatric patients in a Los Angeles Gounty neuropsychiatric Veterans Admin- istration Hospital2. The time interval between date of admission and date of test administration was on the average less than two weeks. No time interval was longer than thirty days.

To keep the sample as homogeneous as possible, Caucasians of Mexican descent were excluded. The Ss represented all incoming patients over a two-year period for whom both the MMPI and a clinical file containing information necessary for this investigation were available. This information consisted of data routinely collected, such as admission date, test date, psychiatric diagnosis, age, occupation, education, religion, marital status, race and number of hospital admissions. No MMPI protocols with more than twelve “don’t know” answers were included.

Each variable investigated was divided into subcategories (Table 1). Infor- mation obtained from .the clinical folders of the patients determined the appropriate subcategory of eachaf the seven variables to which the S belonged. For each analysis Ss belonging to the appropriate subgroups were drawn from all 600 Ss. For each variable, two subcategories at a time were compared with each other on every MMPI item by means of a 2 X 2 chi square item differentiation analysis.’ A greater than chance number of significant items determined whether or not the MMPI discriminated between the paired subcategories in each variable.

RESULTS The levels of significance attained for each comparison of the various

subcategories of diagnosis, religion, education, occupation, marital status, age, and number of VAH admissions tire listed in Table 1. Columns 1 and 2 of this

‘This paper was part of a dissertation submitted to the Faculty of the Graduate School of the University of Southern Califomha in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

‘The author wants to thank Dr. H M. Grayson, Chief, Psychology Department of the Brentwood Veterans Administration H o s p z f o r his kindprmiasion to collect the necessary data.

rSpecial thanka are due to the Honeywell Computer enter of the University of Southern Cali- fornia which did most of the prelimbary work. The Wwtem Data Proceasing Center at UCLA was most involved in the analysis of the data. They granted special permission to conduct the many

necegesry. The Tele-computer Center of the Graduate School of Business Administration of =%= the nivemity of Southern California did moat of the cards to tape transfer.

DEMOGRAPHIC VARIABLES AND MMPI RESPONSES 45 1

TABLE 1. MMPI 1”F.M COMPARI5ONS OF DIFFERENT GROUPS

Factors NI NP L. s. Diagnosis

Neurotic vs. Psychotic Neurotic vs. Pers. Dis. Neurotic vs. Other Psychotic vs. Pers. Dis. Psychotic vs. Other Pers. Dis. vs. Other

Protestant vs. Catholic Catholic vs. Hebrew Protestant vs. Hebrew

Elementary vs. High School Elementary vs. College High School vs. College

$rofessional vs. Clerical Professionals vs. 0 erators Professional vs. Latorers Clerical vs. Operators Clerical vs. Laborers Operators vs. Laborers

Single vs. Married Single vs. Divorced Single vs. Married/Separated Married vs. Divorced Married vs. Married/Separated Divorced vs. Married/Separated

Religion

Education

Occu ation

Marital Status

Age 0-39 vs. 40-49 0-39 vs. 50+ 4049 vs. 50+

1 vs. 2 1 vs. 3 or 4 1 vs. 5+ 2 va. 3 or 4 2vs. 5+ 3 or 4 v8. 5+

Number of VAH Admissions

193 235 .OOl 193 98 05 193 66 ,001 235 98 .OOl 235 66 .01 98 66 . 001

361 170 361

117 117 121

104 ~ . _

104 104 110 110 192

145 145

145

170 38 38

330 121 330

110 192 174 192 174 174

240 145 56 145 56 56

NS NS NS

.05 .001 .OOl

.05 .OOl .001 . 01 .OOl NS

.001 ~.~

,001 ,001 ,001 .10 .10

314 211 ,001 314 72 .001 211 72 .Ol

338 117 .05 338 80 .001 338 52 .OOl 117 80 . CKll 117 80

_.

52 52

. _ _ _ ,001 NS

table show the number of 8 s in each comparison group. Column 3 shows the level of significance reached for each comparison.

The comparison between the neurotic and personality disorder subcategories of psychiatric diagnosis was significant at the .05 level while the psychotic versus “other” comparison was significant a t the .01 level. All other subcategory com- parisons for this variable, viz., neurotic VS. psychotic, neurotic vs. “other”, psychotic vs. personality disorders and personality disorders vs. “other”, reached the .001 level. In contrast, none of the three subcategory comparisons of the religious variable were found to be significant.

Intelligence as evidenced by educational achievement was found to influence MMPI responses. Both the elementary and high school vs. college comparisons reached the .001 level, while the elementary vs. high school comparison was sig- nificant a t the .05 level.

Persons in different occupational classifications too seem to respond dissimilarly, except laborers and operators who respond similarly. Otherwise, laborers, operators, clericals and professionals all differ sigmficantly from each other in the manner they respond to the MMPI.

452 A. G. DEVRIES

The MMPI also appeared to differentiate persons of various marital statuses. Single Ss could be separated at the .001 level from everybody else. The married Ss could be distinguished from the divorced at the same level. The married and the divorced vs. the married but separated comparisons were somewhat ambiguous since they were only significant a t the .10 level.

All age group comparisons were very significant. The 0-39 vs. the 40-49 and the 50+ comparison reached the .001 level, while the 40-49 vs. the 50+ was dif- ferentiated a t the .01 level.

Number of VAH admissions also influenced MMPI responses. Even 1 vs. 2 admissions are differentiated at the .05 level. One admission vs. 3 or 4 and 5+ and also 2 vs. 3 or 4 and 5+ are significant a t the .001 level. Only the 3 or 4 vs. the 5+ admission comparison was not significant.

DISCUSSION As was expected, items of the MMPI did differentiate groups of patients

when they had been categorized according to various psychiatric classification categories. The findings indicate that other variables also influence MMPI responses. The results that intelligence, as evidenced by educational and occupational attain- ment, seems to play an important role in the manner in which Ss respond to MMPI items are consistent with the findings of Brower and Wexner. The significant differences between the various subgroups of marital status, age, and number of VAH admissions was not altogether unexpected since the MMPI items measure adjustment in various behavior areas.

The main implication of these results was that responses to the MMPI are not as straight forward or uncomplicated as has been assumed. The results indicate that demographic variables should be taken into account in the scoring and inter- pretation of the MMPI. The data further suggest that the habit of describing persons in terms of psychiatric syndromes is questionable. The influence of such variables as education, occupation, marital status, age, and number of hospital admissions seems to indicate that collecting items according to their relevance to adjustment in various behavior areas may be a more fruitful approach in under- standing the individual and his problems than the collection of items according to degree of agreement with psychiatric diagnosis.

SUMMARY This study investigated the influence of psychiatric diagnoses, religion, edu-

cation, occupation, marital status, age, and number of VAH admissions on MMPI responses. Each variable was subdivided into several subcategories. The MMPI had been administered to a total of 600 Caucasian male neuropsychiatric veterans sorted into various groups representing selected subcategories of the above variables. The basic design consisted of analyzing two subcategories at a time. For each group the “true” and “false” frequency for each MMPI item was determined. Differences in group frequency for each item were then evaluated for significance by means of a 2 X 2 chi square analysis.

The results showed that all variables except religion influenced MMPI re- sponses. The fact that five other variables, namely education, occupation, marital status, age and number of hospital admissions, as well as psychiatric diagnosis, influenced MMPI responses, suggested that the current MMPI scoring methods and practices of interpretation are unsatisfactory for optimum diagnostic and prediction purposes.

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3. WEXNER, L. B. Relationship of intelligence and the nine scales of the MMPI. J. soc. Psychol., 4. WINFIELD, D. L. The relationship between I.&. scores and MMPI scores. J. SOC. P3ychol., 1953,

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