Comparisons between Category and Magnitude Scaling of Political Opinion Employing SRC/CPS Items

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Abstract
The measurement technique most commonly used by political scientists for determining the direction and intensity of opinion is category scaling–a procedure with serious weaknesses. Recent developments in psychophysics for the magnitude scaling and validation of sensory eontinua offer a powerful alternative to category scaling. Paralleling explicitly the logic and procedures used to scale psychophysically such variables as the loudness of sound and brightness of light, research methods now make it possible and feasible via a simple paper and pencil technique to obtain accurate, precise, cross-modally valid, magnitude measures of the direction and strength of political opinion from respondents in a survey setting.A field survey, pitting category against magnitude measures for a sampling of the most important items employed in the SRC/CPS national election studies, demonstrates that the category scaling of political variables results in (1) the loss of significant portions of information and on occasion (2) the misclassification of respondents. The results of this scale-confrontation study demonstrate the superior utility of magnitude over category scaling for the description and quantitative analysis of political judgments and preferences.