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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)