You can choose a cut score for the items that will maximize sensitivity, maximize specificity, or maximize efficiency. In this instance are the DSM-IV guidelines helpful in determining minimum score that should be used to indicate that a specific criterion was met?Īn empirical approach is to examine diagnostic utility indices at each possible cutting score. One approach would be to go back to the DSM criteria to see if they give any guidance. On the other hand if you make the criteria too lenient you will over diagnose PTSD. How do you determine the minimum score you need to fit the all-or-nothing criteria of the DSM? Is 3 'A little sometimes' enough to meet the criterion? Is 7 'extremely always' necessary to meet the criterion? If you make the criteria too strict then you will underdiagnose PTSD. Participants respond to the PTSD-I items on 7-point scales: No Very Little A little Somewhat Quite a bit Very much Extremely Never Very Rarely Sometimes Commonly Often Very Often Always 1 2 3 4 5 6 7 If you are developing a test to diagnose PTSD then the test must adequately reflect all of the DSM diagnostic criteria.ĭo the items on the PTSD-I scale adequately reflect the DSM-IV criteria? How might you come to quantitative decision about the content validity of the scale? How would you specify the domain for content quizzes in general psychology, for a personality test of extraversion?Ĭontent validity asks the question, 'Do the items on the scale adequately sample the domain of interest?' See handout: DSM-IV Diagnostic Criteria for PTSD In the case of PTSD, the relevant domain of items are specified by the DSM-IV diagnostic criteria for PTSD. The first two questions posed in the overview, 'How would you go about developing a scale to measure posttraumatic stress disorder?' and 'What items would you include in your scale and how would you determine the content validity of the scale?' can be answered by first defining the domain of possible items that are relevant for the scale.

Reliability of test scores