Q. I am a patient and have taken the MMPI-2 and MCMI-III tests. I've heard it's best to wait six months before taking the tests again. Are there any guidelines documented that specify the length of time one must wait before repeating the tests? Would the results be suspect if the tests were repeated within only a month?

A. There are not many data in the literature concerning the absolute minimum time that should elapse between such testing. In one study of normal volunteers who completed the MMPI-2 on two occasions separated by 4 months, Putnam et al (J Pers Assess. 1996 Oct;67(2):341-53) found that, overall, the test had good "test-retest reliability"--in other words, not much changed in four months.

Another study of the MMPI-2 also found moderately good stability of the test results when the re-test interval ranged from 2-75 months (Colatla et al, Psychol Assess. 2001 Dec;13(4):572-6). There are even fewer data regarding the MCMI-III, but some studies indicate that earlier versions of this scale have good test-retest stability even after as little as 35 days, in Vietnam veterans with PTSD (Hyer et al, J Clin Psychol. 1989 Jul;45(4):547-52).

There may be differences, however, in the way symptom scales change, versus the way personality scales change on these tests. For example, repeating the test during active treatment of severe depression may show changes in some symptom scales (such as hopelessness, guilt, etc.) while more stable personality traits (such as cautiousness or shyness) are less likely to change. I might be of more help in answering your question, though, if I understood why such academic issues concern you.

December 2003

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