Background
The Rasch model
Fit statistics
Unidimensionality
Category thresholds
Differential item functioning and item bias
Local independence
Person separation index
Software
RUMM2030
R
Patient-rated wrist evaluation
Methods
Participants
Analysis plan
Results
Item Fit Residuala | Person Fit Residuala | Chi-Squareb | PSIc | UNID T-Testd | ||||||||
Mean | SD | Mean | SD | Value (DF) | p | With | without | |||||
RUMM 2030 | PAIN | Initial | −0.8398 | 1.7301 | −0.4845 | 0.9770 | 24.391 (20) | 0.4969 | 0.9218 | 0.9135 | 4.6800% | |
Final | −0.5336 | 1.1746 | −0.4492 | 0.9127 | 18.5992 (20) | 0.5480 | 0.8781 | 0.8644 | 2.3500% | |||
SPECIFIC | Initial | −0.6052 | 2.1366 | −0.4538 | 1.0702 | 54.0898 (30) | 0.0045 | 0.9220 | 0.9033 | 4.7800% | ||
Final | −0.6266 | 1.5595 | −0.4497 | 0.9686 | 50.3341 (20) | 0.0002 | 0.9016 | 0.8699 | 3.6800% | |||
USUAL | Initial | −0.4119 | 1.7207 | −0.4544 | 0.9432 | 23.1212 (20) | 0.2829 | 0.9208 | 0.8304 | 6.1600% | ||
Final | −0.3182 | 1.8380 | −0.4642 | 1.0076 | 32.1662 (20) | 0.0416 | 0.9217 | 0.8888 | 5.0700% | |||
Item Fit Residuala | Person Fit Residuala | Cronbach’s Alphac | Martin-Loefd | |||||||||
Mean | SD | Mean | SD | Value (DF) | p | |||||||
R | PAIN | Initial | 1.63322 | 1.6195 | −0.0447 | 1.89779 | 0.922 | 370.171(599) | 1.0000 | |||
Final | 1.7807 | 1.6219 | 0.0067 | 1.7558 | 0.872 | 239.851(339) | 1.0000 | |||||
SPECIFIC | Initial | 1.6092 | 0.80491 | 0.12174 | 1.37694 | 0.92 | 392.039(899) | 1.0000 | ||||
Final | 1.7810 | 1.0349 | 0.1273 | 1.3960 | 0.8980 | 246.659(399) | 1.0000 | |||||
USUAL | Initial | 2.73459 | 1.43031 | 0.27866 | 1.84451 | 0.921 | 216.992(399) | 1.0000 | ||||
Final | 2.9494 | 1.9276 | 0.2744 | 2.0210 | 0.9200 | ERROR | n/a |
P1 | P2 | P3 | P5 | S1 | S2 | S3 | S5 | U1 | U2 | U3 | U4 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | −1.19835 | −3.33737 | −3.14927 | −4.03637 | −2.04266 | −1.62154 | −1.53629 | −1.66087 | −2.37087 | −3.82445 | −2.15655 | −2.60126 |
2 | −0.7825 | −1.90999 | −1.77635 | − 1.6777 | −1.18107 | − 1.01629 | −0.88369 | −1.00577 | − 1.64775 | − 2.17004 | −1.56105 | − 1.72138 |
3 | − 0.43429 | − 0.93802 | − 0.78829 | −0.12234 | − 0.63027 | −0.57846 | − 0.53659 | −0.4986 | − 1.03285 | − 1.00179 | − 0.50071 | − 0.57784 |
4 | −0.14711 | − 0.30817 | − 0.10941 | 0.825101 | − 0.30001 | − 0.26485 | − 0.38711 | − 0.11611 | − 0.5064 | − 0.2143 | 0.671801 | 0.638433 |
5 | 0.085634 | 0.092844 | 0.335983 | 1.359987 | −0.10007 | −0.03228 | − 0.32736 | 0.16494 | − 0.0486 | 0.297853 | 1.603822 | 1.736526 |
6 | 0.270551 | 0.378322 | 0.623587 | 1.6777 | 0.059794 | 0.162421 | −0.24946 | 0.367776 | 0.36034 | 0.640062 | 1.942691 | 2.525522 |
7 | 0.414248 | 0.661548 | 0.829091 | 1.97362 | 0.269804 | 0.362451 | −0.0455 | 0.515642 | 0.740206 | 0.917733 | ||
8 | 0.523331 | 1.055814 | 1.028186 | 0.620198 | 0.610989 | 0.392384 | 0.631776 | 1.110787 | 1.236273 | |||
9 | 0.604405 | 1.674409 | 1.296563 | 1.201208 | 0.951222 | 1.172094 | 0.739416 | 1.491874 | 1.701084 | |||
10 | 0.664076 | 2.630623 | 1.709914 | 2.103069 | 1.426333 | 2.401514 | 0.861799 | 1.903255 | 2.417573 |
P1 | P2 | P3 | P4 | P5 | S1 | S2 | S3 | S4 | S5 | S6 | U1 | U2 | U3 | U4 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 1.043976 | −1.4631 | −2.06351 | −2.46048 | −2.418 | −0.15353 | 0.04953 | 0.499969 | −0.4747 | −0.69315 | 0.535126 | 0.987213 | −0.59079 | −0.00357 | − 0.66714 |
2 | 1.752594 | −0.23245 | −0.86288 | −1.12564 | − 0.1572 | 0.65799 | 0.674469 | 1.133881 | 0.491547 | 0.190338 | 0.981171 | 1.802582 | 0.73526 | 0.991608 | 0.494843 |
3 | 2.218781 | 0.691315 | 0.224579 | −0.12167 | 1.110809 | 1.073822 | 1.072723 | 1.510346 | 0.902252 | 0.583649 | 1.249603 | 2.562836 | 1.716522 | 1.699677 | 1.420624 |
4 | 2.475494 | 1.441681 | 0.800079 | 0.548859 | 1.674957 | 1.419342 | 1.439301 | 1.750763 | 1.331451 | 0.90683 | 1.45816 | 3.006317 | 2.381927 | 2.395111 | 1.996307 |
5 | 2.678009 | 1.816132 | 1.242279 | 0.956085 | 1.955841 | 1.697479 | 1.655914 | 1.871979 | 1.534515 | 1.19577 | 1.617096 | 3.333527 | 2.862946 | 2.676178 | 2.444916 |
6 | 2.944427 | 2.079437 | 1.575897 | 1.440948 | 2.207245 | 1.933319 | 1.92746 | 2.069183 | 1.738312 | 1.462372 | 1.74472 | 3.777191 | 3.338287 | 3.088531 | 3.013641 |
7 | 3.320343 | 2.403534 | 1.772552 | 1.592743 | 2.455719 | 2.187103 | 2.045563 | 2.240936 | 1.855133 | 1.623322 | 1.891937 | 4.108978 | 3.63089 | 3.217438 | 3.203522 |
8 | 3.72226 | 3.080658 | 2.197906 | 1.957672 | 2.8992 | 2.467621 | 2.336884 | 2.581512 | 2.052155 | 1.821991 | 2.178131 | 4.219025 | 3.85556 | 3.386261 | 3.356781 |
9 | 3.895294 | 3.950409 | 2.684784 | 2.563202 | 3.275299 | 2.813507 | 2.69101 | 2.901581 | 2.394745 | 2.095001 | 2.525665 | 4.95401 | 4.28183 | 3.747162 | 3.627228 |
10 | 4.305267 | 4.138641 | 3.108856 | 3.136871 | 3.585114 | 2.933807 | 3.047333 | 3.067474 | 2.822845 | 2.536835 | 2.853241 | 5.552765 | 5.144806 | 3.918182 | 3.953888 |
P1 | P2 | P3 | P5 | S1 | S2 | S3 | S5 | U1 | U2 | U3 | U4 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 0.99527 | −1.38327 | −1.91666 | −2.24918 | −0.26633 | −0.05649 | 0.417572 | −0.8226 | 0.950043 | −0.70541 | −0.09256 | −0.78214 |
2 | 1.698029 | −0.24912 | −0.8334 | −0.18796 | 0.583099 | 0.599579 | 1.100006 | 0.085602 | 1.839752 | 0.68454 | 0.94162 | 0.411896 |
3 | 2.177033 | 0.633453 | 0.179718 | 1.025665 | 1.035919 | 1.033722 | 1.533051 | 0.500519 | 2.749237 | 1.748383 | 1.694 | 1.388031 |
4 | 2.44162 | 1.379242 | 0.735809 | 2.033112 | 1.428131 | 1.451569 | 1.824371 | 0.850433 | 3.335907 | 2.521088 | 3.007233 | 2.694489 |
5 | 2.648163 | 1.762115 | 1.175262 | 2.593414 | 1.758087 | 1.709564 | 1.976898 | 1.173981 | 3.810516 | 3.137238 | 4.294647 | 4.302521 |
6 | 2.915131 | 2.033295 | 1.514557 | 3.38736 | 2.051971 | 2.048676 | 2.23764 | 1.482513 | 4.50943 | 3.838715 | ||
7 | 3.283722 | 2.365631 | 1.716705 | 3.653961 | 2.39035 | 2.201935 | 2.478607 | 1.673126 | 4.974701 | 4.290985 | ||
8 | 3.673187 | 3.048065 | 2.155609 | 2.792816 | 2.601654 | 2.988922 | 1.913361 | 5.10434 | 4.617828 | |||
9 | 3.840912 | 3.905731 | 2.652191 | 3.291412 | 3.095306 | 3.45163 | 2.249908 | 5.799042 | 5.150116 | |||
10 | 4.239716 | 4.090668 | 3.078278 | 3.452911 | 3.559296 | 3.67099 | 2.784943 | 6.302765 | 6.009247 |
Pain subscale
Specific activities subscale
Usual activities subscale
Discussion
RUMM2030 | R-ltm | R-eRm | R-TAM | R-lordif | |
---|---|---|---|---|---|
Model Fit Statistics | YES | YES | YES | YES | NO |
Unidimensionality | YES | YESa | YESd | YES | NO |
Category Thresholds | YES | NO | YES | YES | YES |
DIF | YES | YESa | YESa | YES | YES |
Local Independence | YES | YES | YES | YES | NO |
Reliability | YESb | YESc | YESe | YESf | NO |
RUMM2030 | R- ltm/eRm/TAM/lordif | ||
---|---|---|---|
Model Fit Statistics | Pain | Acceptable Item and Person Fit | Acceptable Item and Person Fit |
Specific Activities | Acceptable Item and Person Fit | Acceptable Item and Person Fit | |
Usual Activities | Acceptable Item and Person Fit | Acceptable Item Fit Unacceptable Person Fit | |
Unidimensionality | Pain | Unidimensionality Present | Unidimensionality Present |
Specific Activities | Unidimensionality Present | Unidimensionality Present | |
Usual Activities | Unidimensionality Not Present | Unidimensionality Present | |
Category Thresholds | Pain | Disordered - Item #5 | Ordered |
Specific Activities | Ordered | Ordered | |
Usual Activities | Disordered - Items #3 & 4 | Ordered | |
Differential Item Functioning | Pain | Non-uniform DIF – Item #4 for age | Non-uniform DIF – Item #4 for age |
Specific Activities | Uniform DIF – Item #4 for age | Uniform DIF – Item #4 for age, item #6 for sex | |
Usual Activities | None Detected | Non-uniform DIF – Item #2 for sex | |
Local Independence | Pain | Local Dependency - Items #1 & 5 | No Local Dependency |
Specific Activities | Local Dependency - Items #1 & 2 | No Local Dependency | |
Usual Activities | No Local Dependency | No Local Dependency |