Direct Magnitude Estimation Scales in Public Opinion Surveys

Direct magnitude estimation scales, patterned after S. S. Stevens's work in psychophysics, provide precise, reliable measures. The use of the scales in three surveys demonstrates that they can be used in telephone surveys of a general population. Because the scales are relatively easy to construct, the researcher is able to go into the field more quickly than if he had developed scales through other methods. Since respondents arrange the stimuli on the scale, rather than have the researcher structure the stimuli into categories for respondents, the measures are relatively free of researcher predispositions and bias. The scales' most important use is in providing measures that can be used in theory building. Researchers should benefit from data that allow one to use powerful statistical techniques without violating data assumptions. Diana Stover Tillinghast is an Assistant Professor of Communication at Stanford University. The author is grateful to Kay Magill, Stanford Ph.D. candidate, for her substantial contribution to the work reported here. The surveys were conducted for the San Jose Mercury News. Public Opinion Quarterly ? 1980 by The Trustees of Columbia University Published by Elsevier North-Holland, Inc. 0033-362X/80/0044-377/$1.75 This content downloaded from 207.46.13.129 on Mon, 27 Jun 2016 05:25:02 UTC All use subject to http://about.jstor.org/terms 378 DIANA STOVER TILLINGHAST ducted by the University of Michigan's Survey Research Center. The Laboratory for Behavioral Research at the State University of New York at Stony Brook developed the scales used in one wave of a national panel study designed to test a learning model of support for the U. S. Supreme Court (Lodge et al., 1976). The researchers validated adjectival descriptor scales by using three cross-modality matching procedures-magnitude estimation, hand grip intensity, and sound pressure intensity-demonstrating not only that researchers can build regression-free, psychophysically valid ratio scales to measure the intensity of opinion, but also that these scales can be used in field surveys. The scales discussed in this article were adapted from Stevens's direct, subjective magnitude estimation scale for use in telephone surveys of a general population. In Stevens's early loudness experiments, a subject was presented with a standard tone, which had been assigned a numerical value, and was asked to judge the loudness of other tones in relation to the fixed standard (Stevens, 1956). Later, Stevens (1975) adopted a no-standard procedure, in which subjects assigned any number to the first stimulus and assigned successive numbers in such a way that they reflected their subjective impressions. Although the no-standard procedure is preferred by psychophysicists, the lack of a flxed standard bothers many social scientists (Hamblin, 1974). The scales have the following ratio-scale properties: (1) respondents use the scale to rank order the stimuli, (2) the size of the distances between numbers is known and has meaning, and (3) the scale has an absolute zero, meaning that the number "zero" is assigned when none of the property being measured is possessed (Nunnally, 1967; Torgerson, 1958). However, some researchers argue that subjective magnitude estimation scales provide only interval level measures. For example, Krantz et al. (1971) contend that subjective intensity is an interval scale. The scale provides researchers with two advantages: (1) fundamental measurement and (2) the ability to use the more powerful methods of statistical analyses without violating assumptions of the data (see Torgerson, 1958, and Hamblin, 1974). For more than three decades, researchers have argued whether Likert-type ordinal scales, the most common ordinal scales used in surveys as well as in much social science research, should be treated like interval scales for purposes of analysis (see Hewes, 1978). The beauty of the magnitude estimation scale is that the question of whether it is an interval scale does not arise because the distances between points on the scale are known and represent equal psychological distances along the continuum being measured. This content downloaded from 207.46.13.129 on Mon, 27 Jun 2016 05:25:02 UTC All use subject to http://about.jstor.org/terms DIRECT MAGNITUDE ESTIMATION SCALES 379