VALIDATION DATA

The Cronbach's alpha coefficients for the JOABPEQ ranged from 0.71 to 0.81

The test–retest reliability was confirmed by calculating the kappa and weighted kappa coefficients for each item. Both kappa and weighted kappa were more than 0.50 in all items, except in one item with 0.48. The  lower  95%  CI  exceeded  0.4  in  all  items,  except  in  two  items  with  0.39. This implied that the test–retest reliability of JOABPEQ was acceptable as a measurement of outcome.

In another study, 65 patients showed no change were included in the test-retest analysis. The ICCs for the test-retest reliability were over 0.75 (Q1 Low back pain ICC = 0.751, Q2 Lumbar function ICC = 0.809, Q3 Walking ability ICC = 0.812, Q4 Social life function ICC = 0.832, Q5 Mental health ICC = 0.866), indicating good test-retest reliability

The LoAs of JOABPEQ ranged from 5.70 to 11.05 (Q1 Low back pain 11.05, Q2 Lumbar function 11.15, Q3 Walking ability 10.25, Q4 Social life function 6.65; Q5 Mental health 5.7)

Face  validity  was  checked  in  terms  of  the  completion  rate for filling out the questionnaire. The distribution of the answers for all question items was then checked to ensure that there were no biased answers. Items remaining unanswered accounted for less than 5% in the first test, and there was no skewed distribution, such as floor and ceiling effects.