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Table 2 Psychometric results for the experimental items presented in three different item formats

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

Item Formatb Content Slope Thresholdc Item fit: p (S-X 2)d Imax (at T-score)e Area under the curvef Percentage floor/percentage ceilingg
1 2 3 4 5 Mean
A1 A Do 2 hours of physical labor 3.49 38.6 42.9 47.8 54.9   46.1 0.6523 3.71 (T = 42) 92.9 10.4/41.6
B1a B 4.53 38.0 43.0 48.4 53.1   45.6 0.1133 5.93 (T = 49) 132.9 10.0/42.7
C1 C 4.01 37.7 42.0 46.3 52.7 59.8 47.7 0.0358 4.88 (T = 42) 140.3 10.2/19.6
A2a A Do yard work 4.09 36.3 40.1 44.3 50.7   42.9 0.1473 5.10 (T = 40) 111.1 6.6/57.3
B2 B 4.79 35.7 40.8 46.1 50.6   43.3 0.0751 6.58 (T = 47) 144.0 6.7/52.7
C2 C 4.53 34.3 39.1 43.1 49.3 56.0 44.4 0.0300 6.10 (T = 40) 167.5 5.3/32.1
A3 A Climb several flights of stairs 3.78 35.2 40.3 45.2 52.0   43.2 0.1722 4.28 (T = 41) 107.0 5.8/51.5
B3a B 4.20 34.2 40.8 46.7 51.3   43.3 0.8460 5.16 (T = 48) 126.0 5.1/51.3
C3 C 3.78 33.3 39.8 44.0 51.0 57.1 45.0 0.1174 4.31 (T = 42) 135.0 6.3/25.4
A4a A Go for a walk of at least 15 minutes 3.78 33.2 36.4 40.2 45.5   38.8 0.2497 4.45 (T = 37) 91.3 3.7/73.5
B4 B 4.03 32.1 37.2 42.0 45.8   39.3 0.3555 4.93 (T = 43) 107.0 3.4/71.6
C4 C 3.99 30.3 35.6 39.5 44.9 50.8 40.2 0.0033 4.85 (T = 37) 134.7 3.6/47.5
A5a A Open previously opened jars 1.91 18.8 28.4 37.9    28.4 0.2434 1.10 (T = 28) 36.5 0.9/85.8
B5 B 1.90 12.9 22.8 32.3 39.6   26.9 0.5429 1.10 (T = 33) 39.9 0.3/81.9
C5 C 1.57 5.0 15.5 23.4 34.0 45.4 24.7 0.1877 0.77 (T = 20) 33.6 0.3/62.4
  1. aItem is part of the final Patient Reported Outcomes Measurement Information System Physical Function (PROMIS PF) item bank version 1.0. bFormat 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”). cThresholds are transformed to a T-score of 50 ± 10, where 50 = mean and 10 = standard deviation of the analytic sample; slopes are reported unchanged. d X 2 statistics (S-X 2) were evaluated after adjusting for multiple testing (p < 0.0033). eImax (at T-score) depicts the maximum of item information (upper number) of a given item at the corresponding point on the T-score continuum. fTotal area under the item information curve (IIC) on the empirically observed T-score range in the calibration sample (T-score = 11.1–73.6). gPercentage of participants who answered the item with the lowest (floor) or highest (ceiling) possible response category