PERMAP: An interactive program for making perceptual maps

This article describes a DOS-based computer program for making and testing perceptual maps. The program, PERMAP, uses conventional metric multidimensional scaling techniques. That is, it uses pairwise numerical values (correlations, proximities, dissimilarities, etc.) to construct a map showing the relationship between objects. A unique feature of PERMAP is that it embeds the mapping techniques in an interactive, graphical system that minimizes several difficulties associated with multidimensional scaling practices. It is particularly effective at exposing artifacts due to local minima, incomplete convergence, and the effects of outliers. It can associate various attributes with the resultant groupings and provide line-linking options to help the researcher identify the nature of perceived relationships. Problems involving multiple matrices can be treated using three different aggregation methods. The optional use of weighting factors is available.