絶対尺度構成による児童の9学年にわたる知能発達に関する考察

Abstract

The data analysed in the present study were laboriously collected for ten years by Dr. Hiroshi Kano and other members of the Institute for Science of Labour, and the author is much obliged to Dr. Kano for making the data available for her analysis. The main purpose of the present study is to construct the absolute scale of intelligence developed by Thurstone, L. L., on the basis of raw scores of Suzuki-Binet Intelligence Test administered once a year to apprroximately four or five hundred children for nine successive years since they entered a elementary school in Tokyo in 1946 (first group) and in 1947 (second group) till they graduated from the adjacent junior high school. The original data were rescored for the sake of convenience according to new criteria, among which the following one is important: an item is regarded to be solved by an examinee if it has been solved by him at least once in the preceding testings no matter it is practised to him this time or not.In the absolute scale construction it is assumed that the variable x, representing the mental ability required in solving Suzuki-Binet items, is normally distributed for the examinees at each grade level i, on one dimension with Mi as the mean and σi as the standard deviation, and the critical value ls corresponding to each raw score s is also located on the same continuum, and that only those examinees who possess more or less higher values of x than ls get higher marks than s in testings. However, in the course of analysis it was discovered that the assumption of normality was needed to be slightly modified as it was the case in the author's previous study of absolute scale construction of the same Suzuki-Binet Test data collected by Dr. Jisaburo Suzuki. The two distributions were contrasted and the present one proved to be more leptokurtic (see Fig. 4). The scaled values for ls, Mi and σi were obtained by using the method of successive intervals and the graphical least squares solution developed by Diederich, G. W., and those values were converted to l′s, M′a and σ′a with newly defined origin and unit for being compared with the values ls, Ma and σa obtained from Dr. Suzuki's data (see Table 5, 6 and 7, and Fig. 5).The average growth curve of intelligence developed from the values of M′a and the standard deviation as a function of age were illustrated and compared with those obtained from Dr. Suzuki's data respectively (see Fig. 6 and 7). The two growth curves coincide with each other in spite of the fact that the two samples differ in various respects, in time and district and that the former consist for the most part of the same examinees throughout all the grade levels while the latter consist of different examinees at each age level. The standard deviation σ′a was found to be more invariant from age to age than in the case of σa obtained from Dr. Suzuki's data, and this fact seems to have some connection with the slightly different definitions of the raw scores in the two cases.