Improving the metric quality of questionnaire data

A procedure is proposed whereby questionnaire data, which is usually ordinal in nature and often error-ridden, may be transformed to reduce the error variance in the data and to improve the metric properties of the individual variables. The technique is suggested by a result of Eckart and Young. The properties of the method are investigated by means of a Monte Carlo study. Various matrices were generated representing the usual concept of true scores. These matrices were distorted using two levels of random errors and two kinds of categorization. The distorted matrices were in turn transformed by the proposed methods and compared to the true scores. In all cases an overall measure of similarity reveals the transformed matrices are better approximations to the true scores than the untransformed data. Some properties of the transformation are discussed and some possible applications of the general technique are suggested.