Table 4

Postwebinar survey DIF detection procedure for ordinal data based on adjacent category logit model.

Survey Item	Statistic	P	Adjusted P
Articulating instruments	11.168	0.004	0.021
Multiportal technique	1.607	0.448	0.616
PELIF	15.485	<0.001	0.005
Facet cyst	1.284	0.526	0.643
Low-grade spondylolisthesis	8.130	0.017	0.063
Transforaminal posterolateral HNP	0.836	0.658	0.724
Transforaminal central HNP	3.209	0.201	0.442
Transforaminal lateral stenosis	0.198	0.906	0.906
Transforaminal central stenosis	1.647	0.439	0.616
Transforaminal facet cyst treatment	3.901	0.142	0.391
Transforaminal migrated HNP	2.635	0.268	0.491

Abbreviations: DIF, differential item functioning; HNP, herniated nucleus pulposus; PELIF, percutaneous endoscopic lumbar interbody fusion.
Note. DIF likelihood ratio statistics are estimated by using difNLR and difORD functions. Adjusted P values calculated by the likelihood ratio test using multiple comparison.