Using an analytical hierarchy process (AHP) for weighting items of a measurement scale: a pilot study.

Background: Many clinical scales contain items that are scored separately prior to being compiled into a single score. However, if the items have different degrees of importance, they should be weighted differently before being compiled. The principal aims of this study were to show how the "analytic hierarchy process" (AHP), which has never been used for this purpose, can be applied to weighting the six items of the "London handicap scale", and to compare the AHP to the "conjoint analysis" (CA), which was previously implemented by Harwood et al. (1994) [1].

Design: In order to assess the relative importance of the six items, we submitted AHP and CA to a group of 10 physiatrists. We compared the methods in terms of item ranking according to importance, assessment of fictitious patients based on weights determined by each method, and perceived difficulty by the physiatrist.

Results: For both techniques, "Physical independence" (PHY) was the best-weighted item, but other ranks varied depending on the technique. AHP was better than CA in terms of accuracy (global assessment of the clinical status) and perceived difficulty.

Conclusion: AHP may be used to reveal the importance that experts assign to the items of a multidimensional scale, and to calculate the appropriate weights for specific items. For this purpose, AHP seems to be more accurate than CA.