Table 6.
Item discrimination, difficulty, and average amount of information in item response theory
| Label | SF-36 | SF-12 | ||||
|---|---|---|---|---|---|---|
| Item discrimination (SD) | Item difficulty (SD) | Average amount of information | Item discrimination (SD) | Item difficulty (SD) | Average amount of information | |
| Physical functioning (PF) | ||||||
| PF01 | 2.73 (0.01) | − 1.43 (0.01) | 1.02 | |||
| 0.21 (0.01) | ||||||
| PF02 | 2.73 (0.01) | − 2.53 (0.05) | 0.74 | 2.20 (0.03) | − 3.13 (0.05) | 0.45 |
| − 1.07 (0.01) | − 1.40 (0.02) | |||||
| PF03 | 2.73 (0.01) | − 2.55 (0.05) | 0.73 | |||
| − 1.14 (0.01) | ||||||
| PF04 | 2.73 (0.01) | − 2.05 (0.03) | 0.9 | 2.20 (0.03) | − 2.60 (0.04) | 0.54 |
| − 0.87 (0.01) | − 1.17 (0.01) | |||||
| PF05 | 2.73 (0.01) | − 2.45 (0.04) | 0.65 | |||
| − 1.54 (0.02) | ||||||
| PF06 | 2.73 (0.01) | − 1.88 (0.02) | 0.89 | |||
| − 0.90 (0.01) | ||||||
| PF07 | 2.73 (0.01) | − 1.42 (0.01) | 0.95 | |||
| − 0.25 (0.01) | ||||||
| PF08 | 2.73 (0.01) | − 1.96 (0.03) | 0.89 | |||
| − 0.92 (0.01) | ||||||
| PF09 | 2.73 (0.01) | − 2.51 (0.05) | 0.63 | |||
| − 1.58 (0.02) | ||||||
| PF10 | 2.73 (0.01) | − 1.69 (0.02) | 0.74 | |||
| − 1.20 (0.01) | ||||||
| Role physical (RP) | ||||||
| RP1 | 2.17 (0.02) | 0.77 (0.01) | 0.43 | |||
| RP2 | 2.17 (0.02) | 0.53 (0.01) | 0.43 | 2.32 (0.03) | 0.52 (0.01) | 0.46 |
| RP3 | 2.17 (0.02) | 0.65 (0.01) | 0.43 | 2.32 (0.03) | 0.63 (0.01) | 0.46 |
| RP4 | 2.17 (0.02) | 0.52 (0.01) | 0.43 | |||
| Bodily pain (BP) | ||||||
| BP1 | 0.45 (0.01) | − 10.26 (0.48) | 0.06 | |||
| − 8.08 (0.31) | ||||||
| − 4.60 (0.16) | ||||||
| − 1.33 (0.06) | ||||||
| 1.24 (0.06) | ||||||
| BP2 | 0.45 (0.01) | 0.32 (0.05) | 0.05 | 1.06 (0.02) | 0.18 (0.02) | 0.24 |
| 4.65 (0.17) | 2.40 (0.04) | |||||
| 7.46 (0.28) | 3.83 (0.07) | |||||
| 10.00 (0.44) | 5.28 (0.12) | |||||
| General health (GH) | ||||||
| GH1 | 1.76 (0.01) | − 3.05 (0.05) | 0.76 | 0.91 (0.01) | − 1.80 (0.03) | 0.24 |
| − 1.11 (0.02) | 0.21 (0.02) | |||||
| − 0.13 (0.01) | 1.72 (0.03) | |||||
| 1.2 (0.01) | 4.93 (0.09) | |||||
| GH2 | 1.76 (0.01) | − 2.33 (0.03) | 0.73 | |||
| − 1.46 (0.02) | ||||||
| − 0.23 (0.01) | ||||||
| 0.54 (0.01) | ||||||
| GH3 | 1.76 (0.01) | − 2.77 (0.03) | 0.68 | |||
| − 2.14 (0.02) | ||||||
| − 0.89 (0.01) | ||||||
| 0.35 (0.01) | ||||||
| GH4 | 1.76 (0.01) | − 2.43 (0.03) | 0.67 | |||
| − 1.55 (0.02) | ||||||
| − 0.52 (0.01) | ||||||
| 0.17 (0.01) | ||||||
| GH5 | 1.76 (0.01) | − 2.75 (0.03) | 0.71 | |||
| − 2.04 (0.02) | ||||||
| − 0.78 (0.01) | ||||||
| 0.57 (0.01) | ||||||
| Vitality (VT) | ||||||
| VT1 | 0.74 (0.00) | − 2.43 (0.04) | 0.17 | |||
| 0.29 (0.03) | ||||||
| 1.68 (0.03) | ||||||
| 3.33 (0.05) | ||||||
| 4.71 (0.07) | ||||||
| VT2 | 0.74 (0.00) | − 2.74 (0.04) | 0.17 | 0.91 (0.01) | − 2.36 (0.01) | 0.25 |
| − 0.40 (0.03) | − 0.35 (0.02) | |||||
| 1.22 (0.03) | 1.07 (0.02) | |||||
| 2.89 (0.04) | 2.50 (0.04) | |||||
| 3.90 (0.07) | ||||||
| VT3 | 0.74 (0.00) | − 4.73 (0.07) | 0.16 | |||
| − 3.10 (0.04) | ||||||
| − 1.97 (0.03) | ||||||
| − 0.50 (0.03) | ||||||
| 2.10 (0.03) | ||||||
| VT4 | 0.74 (0.00) | − 4.26 (0.06) | 0.18 | |||
| − 2.55 (0.04) | ||||||
| − 1.36 (0.03) | ||||||
| 0.15 (0.03) | ||||||
| 2.93 (0.04) | ||||||
| Social functioning (SF) | ||||||
| SF1 | 0.50 (0.01) | − 1.68 (0.06) | 0.07 | |||
| 2.80 (0.08) | ||||||
| 5.92 (0.17) | ||||||
| 8.66 (0.29) | ||||||
| SF2 | 0.50 (0.01) | − 6.35 (0.18) | 0.07 | 1.07 (0.02) | − 3.42 (0.06) | 0.28 |
| − 4.73 (0.13) | − 2.58 (0.04) | |||||
| − 3.48 (0.10) | − 1.92 (0.03) | |||||
| − 2.06 (0.07) | − 1.15 (0.02) | |||||
| − 0.01 (0.05) | − 0.02 (0.02) | |||||
| Role emotional (RE) | ||||||
| RE1 | 1.82 (0.02) | 0.35 (0.01) | 0.36 | |||
| RE2 | 1.82 (0.02) | 0.23 (0.01) | 0.36 | 1.63 (0.02) | 0.24 (0.01) | 0.31 |
| RE3 | 1.82 (0.02) | − 0.07 (0.01) | 0.36 | 1.63 (0.02) | − 0.07 (0.01) | 0.32 |
| Mental health (MH) | ||||||
| MH1 | 0.78 (0.00) | − 4.35 (0.07) | 0.19 | |||
| − 2.59 (0.04) | ||||||
| − 1.53 (0.03) | ||||||
| − 0.33 (0.03) | ||||||
| 1.50 (0.03) | ||||||
| MH2 | 0.78 (0.00) | − 4.49 (0.07) | 0.18 | |||
| − 2.99 (0.04) | ||||||
| − 2.12 (0.03) | ||||||
| − 1.01 (0.03) | ||||||
| 0.82 (0.03) | ||||||
| MH3 | 0.78 (0.00) | − 11 (–) | 0.19 | 0.79 (0.01) | − 3.94 (0.06) | 0.2 |
| − 2.84 (0.07) | − 2.24 (0.03) | |||||
| − 0.42 (0.03) | − 0.82 (0.03) | |||||
| 1.03 (0.03) | 0.55 (0.03) | |||||
| 2.72 (0.04) | 2.91 (0.04) | |||||
| MH4 | 0.78 (0.00) | − 4.83 (0.08) | 0.18 | 0.79 (0.01) | − 4.73 (0.07) | 0.18 |
| − 3.18 (0.05) | − 3.18 (0.04) | |||||
| − 2.15 (0.03) | − 2.19 (0.03) | |||||
| − 0.82 (0.03) | − 0.88 (0.03) | |||||
| 2.04 (0.03) | 2.00 (0.03) | |||||
| MH5 | 0.78 (0.00) | − 11.18 (–) | 0.18 | |||
| − 1.35 (0.04) | ||||||
| 0.84 (0.03) | ||||||
| 2.05 (0.03) | ||||||
| 3.48 (0.05) | ||||||
| HT | 0.91 (0.00) | − 4.84 (0.09) | 0.23 | |||
| − 2.59 (0.04) | ||||||
| − 0.23 (0.02) | ||||||
| 1.25 (0.03) | ||||||
SD standard deviation