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Table 4 Analysis of variance (ANOVA) and relative validity (RV)

From: Varying the item format improved the range of measurement in patient-reported outcome measures assessing physical function

Subgroup comparisons General health groups considered for ANOVAa Full bank (124 items)b Format Ac (5-item short form) Format B (5-item short form) Format C (5-item short form)
Poor Fair Good Very good Excellent F RV F RVd (95% CI) F RV (95% CI) F RV (95% CI)
a. Full sample X X X X X 16,957 1 .0 15,582 0.92 (0.91–0.93) 16,139 0.95 (0.94–0.96) 15,712 0.93 (0.92–0.94)
b. Average PF   X X X   6960 1 .0 6246 0.90 (0.88–0.91) 6473 0.93 (0.92–0.94) 6349 0.91 (0.90–0.93)
c. Below-average PF X X     3818 1 .0 3421 0.90 (0.87–0.92) 3491 0.91 (0.89–0.94) 3564 0.93 (0.91–0.96)
d. Above-average PF     X X 1870 1 .0 1476 0.79 (0.74–0.84) 1467 0.78 (0.74–0.83) 1720 0.92 (0.88–0.96)
  1. aSubgroups marked X were considered for calculating F values (ANOVA); n = 10,000 per subgroup. bFinal Patient Reported Outcomes Measurement Information System Physical Function (PROMIS PF) item bank version 1.0. cFormat A: “Are you able to …” (five-category response scale from “Without any difficulty” to “Unable to do”); format B: “Does your health now limit you in …” (five-category response scale from “Not at all” to “Cannot do”); format C: “How difficult is it for you to …” (six-category response scale from “Very easy” to “Impossible”). dRV calculation: (ANOVA F values derived from using a format-specific 5-item short form)/(ANOVA F values derived from using full bank scores)