Table 5.

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.