The DSM-IV criteria appear to have acceptable reliability. There are two types of reliability. The first focuses on internal consistency across the constituent items, essentially reliability across items on a single administration. There is evidence that the DSM criteria generate items that are related to a single construct [31–33], although a unifactorial solution may not be optimal [11, 34]. There is evidence that the interviewer administered format is less internally consistent (α ≈ .50 with the DIS-interviewer administered format) [35] than paper-pencil formats (α ≈ .80)[36]. The second type of reliability is test-retest reliability, and concerns the repeatability of the test performance over time. Importantly, there is evidence that DSM-IV based assessments have acceptable test-retest reliability and that the paper-pencil and structured interview administration formats are meaningfully related (.69 – .79) [37]. A caveat is that stability across repeated testing (test-retest reliability) is not always a desirable characteristic in a measure, because stability can be achieved by making the measure insensitive to change (consider the case of using age-of-onset of smoking as a measure of dependence). An ideal measure is
