Description and Critique of the MMPI
Description and Critique of the MMPI
The Minnesota Multiphasic Personality Inventory (MMPI) one of the most popular personality tests today is often the standard to which others are compared (Cohen & Swerdlik, 2010). It was designed to aid in the diagnosis and prediction of mental illness in patients 14 years of age and older, in a more objective manner. The MMPI is atheoretical and therefore was not created based on a specific theoretical background. It initially contained 566 true and false questions divided into 10 clinical scales, which were derived through research of various sources including personality items that had been previously published by others, textbooks and psychiatric case studies and reports (Cohen & Swerdlik, 2010). The construction of the test relied heavily on empirically derived items. The test developers presented the scale items to two groups, the clinical criterion group which consisted of members of a population who were believed to have the same diagnostic condition, mostly psychiatric inpatients, and a normal control group who were non-diagnosed individuals. This group is also known as the standardized sample and included 1500 people from a variety of backgrounds and locations. After the items were administered to these groups any items that differentiated the two were kept for further consideration. It was from these items that the scales of the MMPI were created (Cohen & Swerdlik, 2010). Over time the developers became aware of research regarding problems with self-report methods and developed three validity scales which would indicate deviant responses that could affect the test results. These scales are known as the L (Lie) scale includes 15 items in which people may attempt to portray themselves in a more favourable light. The F (Frequency scale) includes 64 items that would not normally be endorsed by normal individuals. The K (Correction) scale also attempts to indicate portrayal of oneself in a more favourable way but in a more subtle manner, a high score indicates defensiveness. Another scale that was included was the “Cannot Say” scale which measures the number of items that the test taker did not mark a response to or marked “cannot say”. If this applies to 30 or more questions the test is no longer considered valid, some indicate that a mark of 10 on this scale is cause for concern. The MMPI consists of 550 true or false questions with some versions including 16 repeated questions, totalling 566 questions. Scores are in the form of T scores in which the mean is 50 and the standard deviation is 10. The MMPI also includes content scales, their purpose is to group similar test items together to give the impression that all items in the scale are related. Hundreds of supplementary scales have also been devised since the original test was published, which focus on a variety of areas (Cohen & Swerdlik, 2010). Initially, the MMPI was administered as a paper and pencil test, but is now available online, on disk for computer-based use, on index cards and even in an audio format. The audio format is designed for use with individuals who have difficulty reading and are instructed to vocally answer the questions. For administration of all other versions it is imperative that the test takers have at least a grade six reading ability. There is no time limit (Cohen & Swerdlik, 2010). It is no longer necessary for people to manually score the test; a computer scoring service is now available and is the method most users choose. Analyses provided can range from a numerical or graphical representation or may include detailed descriptions of the results. As for interpretation of the results, they were not meant to be based on single scores but on the patterns and profiles that emerged from all of the results together, however this proved to be extremely difficult. Since then two systems have been developed to...
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