Table 3.
Summary of Rasch analyses assessing the overall model fit performed in three stages along with the iterative revisions
| Analysis | Item residual | Person residual | Chi-square interaction | Psi | T test n (%, CI) | ||||
|---|---|---|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | Value | DF | P | |||
| Original version | 0.355 | 2.413 | −0.296 | 1.464 | 371.1 | 160 | < 0.001 | 0.84 | 15 (3.35%, 1.8–4.8%) |
| Thresholds ordered | −0.052 | 1.880 | −0.347 | 1.416 | 330.5 | 160 | < 0.001 | 0.85 | 16 (3.57%, 2–5.1%) |
| Items 13, 18 deleted | 0.322 | 1.561 | −0.383 | 1.521 | 180.3 | 144 | 0.022 | 0.85 | 16 (3.80%, 2.2–5.4%) |
Values highlighted in bold in the probability column indicate statistical significance at the 0.05 level after Bonferroni adjustment for the original version, with thresholds ordered set at 0.0025 for 20 items and with two items deleted set at 0.0027 for 18 items
Independent t tests were performed with eight items divided into two subsets representing most diversity along a continuum. Each subset included > 15 thresholds for the original version and > 12 thresholds for the version with thresholds ordered and with two items deleted
DF degrees of freedom
P probability value
Psi Person separation index reported with extrapolated person values included
CI confidence interval reported as lowest to highest