ATTITUDES: AN A POSTERIORI APPROACH
We are to examine in this chapter a second major technique for the measurement of attitudes. This is the method of summated ratings, developed by Rensis Likert. In the last chapter we called this method an a posteriori approach, because, in contrast to the Thurstone technique of equal-appearing intervals, scale values are determined after, rather than before, the collection of attitude data.
Likert first described the method of summated ratings in a monograph published in 1932. In this monograph, "A Technique for the Measurement of Attitudes," Likert describes the development of scales to measure attitudes toward internationalism, imperialism, and the Negro. The first two of these scales are now out of date, but the third scale, attitude toward the Negro, can still be used.
A second major report on the use of the method of summated ratings is contained in the monograph "Personality in the Depression." This monograph was prepared by Rundquist and Sletto and was published in 1936. In this monograph Rundquist and Sletto show how they applied Likert's technique in the development of scales to measure general morale, inferiority, family relations, respect for law, economic conservatism, and attitude toward the value of education. A description of the methods used in the development of these scales will serve two purposes. It will illustrate, better than some of Likert's own data, the method of summated ratings. And it will put us in a position to understand the development of one of the personality inventories that we plan to discuss in Chap. 7.
The basic assumptions in the method of summated ratings are that each statement in our scale covers the entire attitude continuum; that specific points on this scale can be indicated by alternative responses to each statement; that the points to be represented by the alternative responses can be determined from a knowledge of the percentage of subjects who give each of these responses; and