Postwebinar survey DIF detection procedure for ordinal data based on adjacent category logit model with orthopedic surgeons as the reference and neurosurgeons as the focal group l.
| Procedure | Statistic | P | Adjusted P |
| Endoscopic complex lumbar revision strategies | 12.111 | 0.002 | 0.009 |
| Endoscopic debridement of grades 1–3 spondylolytic spondylolisthesis | 0.144 | 0.931 | 0.931 |
| Posterior cervical endoscopic foraminotomy for disc herniation and bony stenosis | 6.035 | 0.049 | 0.098 |
| Posterior endoscopic single and multilevel decompression of cervical spondylotic myelopathy | 4.020 | 0.134 | 0.179 |
Abbreviation: DIF, differential item functioning.
Note. DIF likelihood ratio statistics are estimated by using difNLR and difORD function. The adjusted P values were calculated by likelihood ratio test using multiple comparison.