The HLQ included 14 items from the Delusion Symptoms States Inventory [DSSI; Bedford et al., 1976] scales, and 19 from the 90-item Symptom Checklist [Derogatis et al., 1973] rephrased to match the DSSI: “Recently I have had …” rather than “In the past two weeks …” A factor analysis [see Gillespie et al., 1999] derived nine depression items (SelfRepDep) scored on a four-point scale: (0) “not-at-all,” (1) “a little,” (2) “a lot,” (3) “unbearably.” The IRT analyses treated these individually; the ordinal regressions used their summed score which was skewed so recoded to the four-point ordinal scale giving approximately equal frequencies: 0 = 0, 1 = 1, 2 = 2 or 3, and 3 = 4 or more.
