A HETEROGENEITY TEST STATISTIC OF K CANONICAL CORRELATIONS AND ITS APPLICATION TO PRENATAL EXPOSURE

In multivariate analysis, the interrelations between two sets of measurements made on the same subjects are examined by canonical correlation methods. The canonical correlation is well known as the maximum correlation between linear functions of the two sets of variables. Interest herein is to test a heterogeneity of canonical correlations of k groups based on school performance data of prenatally exposed survivors of the atomic bombing. Because the most important single factor in determining the nature and extent of the insult to the developing embryo or fetus resulting from exposure to ionizing radiation is the developmental age (gestational age), gestational ages have been grouped so as to reflect these known phases in normal development. Such a heterogeneity test statistic of k canonical correlations has been applied to the school performance data. In the findings by gestational weeks, the largest canonical correlation only was significant different from zero; but all the remaining canonical correlations were not significant. The results of multivariate analysis based on canonical and multivariate correlations disclosed effect of radiation exposure to the development of the brain in the 8-15 week and 16-25 week groups. This tendency appeared to be stronger at lower grades.