Postwebinar survey DIF detection procedure for ordinal data based on adjacent category logit model: likelihood ratio χ2 statistics.
| Procedure | Statistica | P | Adjusted P |
| UBE STEN | 1.9706 | 0.373 | 0.906 |
| PEID | 0.0565 | 0.972 | 0.972 |
| UBE LAM HNP | 0.7903 | 0.674 | 0.906 |
| UBE LAM STEN | 16.2144 | <0.001 | 0.002 |
| Endo + ISP | 0.6434 | 0.725 | 0.906 |
Abbreviations: DIF, differential item functioning; Endo + ISP, transforaminal endoscopic decompression with simultaneous interspinous process spacer for lateral canal stenosis; PEID, percutaneous interlaminar endoscopic decompression for lateral canal stenosis; UBE LAM HNP, unilateral biportal endoscopic laminectomy for herniated disc; UBE LAM STEN, unilateral biportal endoscopic laminectomy for central stenosis; UBE STEN, unilateral biportal endoscopic decompression for lateral canal stenosis.
Note. The adjusted P values were adjusted by likelihood ratio test using multiple comparison.
↵a DIF likelihood ratio statistics are estimated by using difNLR and difORD function.