There are all manner of other ways to stumble into this pitfall. We let ourselves be controlled by data, rather than by theory, ("What does it mean to be depressed?"), Incorrectly keyed! Since 51% of the "depressed" sample responded "false", the key value would be "false",Īnd consequently the normal sample would be reported as more depressed than the "depressed" sample! Of course, if This item would differentiate the samples well, but it would be Imagine an item to which none of the normal sample responded "true", but 49% of the Key is the direction (true or false) that the "depressed" patient sample endorsed more frequently. How are the items used to identify depression? The empirical assignment is built on the rule that the Into this category because it emphasizes the mental state not of the subject, but of those with whom the
"I sometimes keep on at a thing until others lose their patience with me" falls This empirical method is precarious - accidental differences between samples will be mistaken for Sample of "normal" subjects from some other sample of patients exhibiting symptoms of depression. How were these items chosen? The selection criterion for each item was that it differentiated some Subject that agree with the key is intended to indicate the severity of the subject's depression.
20 items, like "I cry easily", are keyed "true".ģ7 items, like "I am happy most of the time" are keyed "false". 1989).Ĭonsider the "depression" scale of 57 true/false items. Which Way is Up? Correctly keying the MMPI-2 Which Way is Up? Correctly keying the MMPI-2Ī pitfall of empirically-based data analysis, into which the unwary easily stumble, is uncovered by even aĬursory Rasch analysis of the Minnesota Multiphasic Personality Inventory-2 (Butcher et al.