Historical Development
The Minnesota Multphasic Personality Inventory (MMPI) was first published in 1943. The test authors were Starke Hathaway, Ph.D, and J. Charney McKinley, M.D. At the time, psychologists were not involved in psychotherapy. Their primary role was to administer tests and to attach diagnostic labels to patients. The MMPI was one of the first tests to use criterion keying of items. Prior tests were based on theoretical notions of symptoms, underlying causes of disturbance, etc. General Use
General Use
The MMPI was an attempt to make a more objective test. The questions in the MMPI are easy to comprehend, and all the respondent (patient) must do is say that a particular statement is true of them, is not true of them, or does not apply to them.
Clinical psychologists use it in their practices. Virtually every clinical psychologist is taught to use the MMPI in graduate school. Current thought is that the scales must mean something, and that research and experience with people who show certain scores give meaning to the scores. The MMPI and the revised MMPI-2 are by far the most widely used questionnaires in psychological assessment. Their principle focus is on identifying pathological illness, disorders and problems. The MMPI does not identify a subject's strengths and abilities.
After a decade or so of experience with the MMPI, people realized that it didn't do what it was designed to do very well. That is, scores on the scales didn't tell the clinician what label to assign a patient. Many patients had high scores on several scales, and some normals had a high score on at least one of the scales. Some of the scales turned out to be highly correlated, indicating that the test did not have the factor structure intended by the authors. As a result, the original scale names have been replaced by numbers, so that the individuals with high scores on various scales will be less likely to be inappropriately labeled.

Norms/Population

MMPI 2 Norms
Norms: A nationally representative community sample of adult men and women (1,138 males and 1,462 females between the ages of 18 and 80 from several regions and diverse communities within the U.S.)
Norms: MMPIA
The MMPI-A normative and clinical samples included 805 males and 815 females, ages 14 to 18, recruited from eight schools across the United States and 420 males and 293 females ages 14 to 18 recruited from treatment facilities in Minneapolis, Minnesota, respectively. Norms were prepared by standardizing raw scores using a uniform t-score transformation, which was developed by Auke Tellegen and adopted for the MMPI-2. This technique preserves the positive skew of scores but also allows percentile comparison.[16]

reliability,
3. Evidence of Reliability
The validity and reliability is based in part of the original MMPI. According to Test Critiques, as a whole, the test was found to be valid in measuring what its claims to be measuring. Test –retest reliabilities for the validity, clinical, supplementary, and content scales range from .67 (Scale 6, Paranoia) to .92 (Scale 0, Introversion-Extraversion) (Keyser & Sweetland, 1994). and standard error;
Validity Scales
The authors also developed four validity scales to detect "deviant test-taking attitudes." The following are specifics on the scales:
1. The "Cannot Say" scale. This is the simple frequency of the number of items omitted or marked both true and false. Large numbers of missing items call the scores on all other scales into question.
2. The L scale, originally called the "Lie" scale. This was an attempt to assess naive or unsophisticated attempts by people to present themselves in an overly favorable light. These items were rationally derived rather than criterion keyed. An example item is "I do not read every editorial in the newspaper every day." Only somebody playing Batman will say "false" to this item.
3. The F scale. This is a deviant, or rare response scale. The approach was