Table 2.
Items with DIF and their McFadden’s pseudo R2 and IRT parameters.
| Item bank | Item with DIF | McFadden’s pseudo R2 | Slope; threshold parametersa | Included in CAT simulation | Included in SF |
|---|---|---|---|---|---|
| Physical function | PFB5r1: Does your health now limit you in hiking a couple of miles (3 km) on uneven surfaces, including hills? | R212 = 0.0208 | NL: 3.29; −1.56, −1.02, −0.57, −0.12 | 45% | |
| R223 = 0.0009 | US: 4.04; −1.12, −0.77, −0.26, 0.22 | ||||
| PFC29: Are you able to walk up and down two steps? | R212 = 0.0341 | NL: 2.29; −2.01, −1.74, −1.06 | 0% | ||
| R223 = 0.0023 | US: 3.08; −2.57, −2.08, −1.57 | ||||
| Pain behavior | PAINBE50: When I was in pain I moved my limbs protectively | R212 = 0.0236 | NL: 3.64; −0.73, 0.59, 0.99, 1.54, 2.15 | 0% | |
| R223 = 0.0012 | US: 3.81; −0.83, 0.28, 0.60, 1.17, 1.63 | ||||
| PAINBE26: Pain caused me to curl up in a ball | R212 = 0.0356 | NL: 4.72; −0.69, 0.52, 0.90, 1.47 | 0.002% | ||
| R223 = 0.0048 | US: 4.72; −0.74, 0.95, 1.31, 1.83 |
aThe bold population had lower thresholds compared to the other population, indicating that this population endorses higher item response categories at the same level of the domain.
CAT: Computerized Adaptive Test; SF: short form; NL: Netherlands; US: Unites States.