A NOTE ON NORMS FOR SCATTER ANALYSIS ON THE WECHSLER INTELLIGENCE SCALES

BENJAMIN ALIMENA

Manhattan. College

In 1951, this author(’) described a method of determining norms for the analysis of scatter on the Wechsler Scales. The revision of the adult scale, however, seems to make these norms ob- solete.

Wechsler (a), in recognizing the basic limitations in the scoring system of the earlier Bellevue scales for the study of scatter, constructed an alternate scoring system(2) which may be utilized for this purpose (Wechsler Manual 1955) in that the “scale score equivalents” (Tables 19-28) are comparable throughout the entire scale. This alternate scoring system achieves one of the major objectives of the earlier paper. The‘ com- parability of scale scores allows one to apply normal curve functions to the deviations of sub- test scores from the subject’s general level of ability in order to evaluate their statistical sig-

TABLE 1. SHOWING THE METHOD OF ESTABLISH- ING NORMS FOR THE STUDY OF SCATTER

Scale score equivalents Subtest I& z-scores

1 56 -3.87 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20

~~

60 -3.44 65 -3.01 70 -2.58 75 80 85 90 95

100 105 110 115 120 125 130 135 140 144 150

-2.15 -1.72 -1.29 - .86 - .43

0.00 + .43 + .86 +1.29 +1.72 +2.15 +2.58 +3.01 +3.44 +3.87 +4.30

nificance. The table of norms may be applied to both the WISC and the WAIS for this purpose.

As a summary of the method the following pro- cedure is presented. The subtest scale score equivalents are converted into subtest ‘intelli- gence quotients’. These latter scores have been calculated according to Wechsler’s method of de- termining deviation intelligence quotients and are presented in columns 1 and 2 of Table 1. Sec- ondly, to determine the degree of scatter (gen- erally referred to as trait variability), divide the mean of the individual’s ‘subtest quotients’ into each of these contributing scores. Due to the fact that the original distribution of the “scale score equivalents” is the same as the original dis- tribution of the “scale scores”, in that these scores are conversions of the original raw scores, and each of the resultant score scales have their various means set a t 10 and the standard devia- tions set a t 3, the general average of the mean ‘subtest quotients’ for all age groups may be estimated t o be 100, the same as the mean IQ for all age groups.

Column 2, therefore, serves a second purpose. Find the subtest deviation quotients (the scores calculated when the mean of the individual’s ‘subtest quotients’ is divided into each of the contributing scores) in that column and evaluate it as a z-score in column 3. The S. D. used in determining z-scores in column 3 was 2.33. This figure is 77.5% of the subtest S.D., and it re- flects the relationship between trait variability and individual variability which was discussed in the earlier paper.

REFERENCES 1. ALIMENA. B. Norms for scatter analvsis on ~.

the Wechsl& Intelligence Scales. J . c&. Psy-

2. WECHSLER, D. Manual for the Wechsler Adult Intelliaence Scale. New York: The

c ~ o Z . , 1951, 7 , 289-290.

Psychologicd Corp., 1955. 3. WECHSLER, D. The Measurement and Ap-

praisal of Adult Intelligence. Baltimore: The Williams and Wil.<ins Co. 1956.