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Fig. 2 | Health and Quality of Life Outcomes

Fig. 2

From: Comparing five depression measures in depressed Chinese patients using item response theory: an examination of item properties, measurement precision and score comparability

Fig. 2

Test information functions (TIFs) and standard errors of measurement (SEMs) Curves. Note. Solid lines; left y-axis = total information aggregated across all items within the corresponding scale along the depression level (θ) ranging from −3 to 3. Dashed lines; right y-axis = standard error of measurement at scale level along the depression level (θ) ranging from −3 to 3. The test information of 10 derived from item response theory on the left y-axis is approximately equivalent to the reliability of .90 derived from classical test theory.BDI-II = Beck Depression Inventory–II; CES-D = Center for Epidemiologic Studies Depression Scale; PHQ-9 = 9-item Patient Health Questionnaire; DASS-Depression = Depression subscale of the 21-item Depression, Anxiety and Stress Scale; HADS-Depression = Depression subscale of the Hospital Anxiety and Depression Scale

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