Table 2.
Clinimetric properties of the AM item for various exclusions
Item to Total Correlation | Cronbach’s Alpha if Item Omitted | IRT Discrimination | MAD | |
---|---|---|---|---|
SITE RATINGS | ||||
Original Sample (n = 208 patients) | 0.011 | Increase | 0.09 | N/A |
Sufficient Duration and Severity (n = 145 patients) | 0.153 | Decrease | 0.341 | N/A |
Sites with Greater Than 10 Patients (n = 137 patients) | 0.182 | Decrease | 0.409 | N/A |
Reverse Scoring Omitted (n = 127 patients) | 0.251 | Decrease | 0.467 | N/A |
VIDEO RATINGS | ||||
Video Ratings with 5 Raters (n = 80 patients, 400 ratings) | 0.231 | No Change | 0.718 | 0.91 |
Sufficient Duration and Severity (n = 60 patients, 300 ratings) | 0.405 | Decrease | 1.163 | 0.75 |
Reverse Scoring Omitted (n = 60 patients, 273 ratings) | 0.444 | Decrease | 1.29 | 0.68 |
Clinimetric properties of the AM item, before and after excluding patienls with insufficient severity and duration of AM trial and raters using reverse scoring (IRT = item response theory; MAD = mean absolute difference).