The Neck Disability Index is the most frequently evaluated question naire and shows positive results for internal consistency , content validity , structural validity , hypothesis testing , and responsiveness , but a negative result for reliability .
The other question naires show positive results , but the evidence for each measurement property is mostly limited , and at least 50 % of the information on measurement properties per question naire is lacking .
Purpose To critically appraise and compare the measurement properties of the original versions of  neck-specific question naires .
Sensitivity to Change and Internal Consistency of the Northwick Park Neck Pain Questionnaire and Derivation of a Minimal Clinically Important Difference
Objectives To estimate the sensitivity to change and internal consistency of the Northwick Park Neck Pain Question naire ( NPQ ) and derive its minimal clinical ly important difference ( MCID ) . Methods Data on 311 participants in a r and omized controlled trial of physical therapy for neck pain were analyzed , between baseline and 6-month follow-up . Cronbach α was used to estimate internal consistency . Three methods of evaluating the NPQ 's sensitivity to change were used ; Cohen 's effect size , st and ardized response mean , and Guyatt 's responsiveness statistic . The smallest change on the NPQ that can be construed as clinical ly important ( the MCID ) was obtained by ( 1 ) comparing values derived from different methods that account for the measurement error of the question naire with improvements in other neck pain-specific measures , and then ( 2 ) examining the impact of the addition of an independent measure ( “ anchor ” ) relating to participants ' subjective rating of improvement . Results Cronbach α was 0.79 for the whole scale . Using all participants , Cohen 's d was 0.78 , st and ardized response mean was 0.71 , and Guyatt 's responsiveness statistic was 0.93 . Using only participants who stated they had improved , the estimates were 1.35 , 1.27 , 1.45 , respectively . The MCID for the NPQ was determined as a 25 % reduction in score from baseline together with a patient 's global rating of their neck pain of at least “ better . ” Conclusions These results show high internal consistency and sensitivity to change for the NPQ , and provide an MCID that allows participants with varying levels of severity to demonstrate improvement
The Neck Disability Index is the most frequently evaluated question naire and shows positive results for internal consistency , content validity , structural validity , hypothesis testing , and responsiveness , but a negative result for reliability .
The other question naires show positive results , but the evidence for each measurement property is mostly limited , and at least 50 % of the information on measurement properties per question naire is lacking .
Purpose To critically appraise and compare the measurement properties of the original versions of  neck-specific question naires .