Using the same four-fold method we may calculate the correlation between deficiency and juvenile delinquency among Minneapolis boys. It is necessary to make a good estimate of the proportion of boys who annually become delinquent in Minneapolis for the first time, and of the proportion of these boys who are correspondingly deficient. Fortunately these comparisons can be made fairly accurately on the basis of the reports for the year 1915 and of our tests of juvenile delinquents. We may use a minimum and a maximum estimate of deficiency among the delinquents corresponding to those that tested below borderlines which represented the lowest 0.5% and the lowest 1.5% of the population of corresponding ages. We need to assume that the frequency of tested deficiency among the boys found delinquent would correspond within these limits to the frequency among the Glen Lake group. The indices for the amount of school retardation in these two groups (Table XIV) indicate that this is a liberal estimate. We must also assume that the proportion of juvenile delinquents for the year 1915 may be regarded as typical for a series of years. The number of new cases of boys in juvenile court in 1915 was within 18 of the median number for the last four years. The result of these estimates is Table XIX for the minimum estimate of deficiency. A similar table for the maximum estimate of deficiency would be the same, except that the proportion of all boys of these ages who were deficient would be 1.5%, and of the delinquent group, 7.3%. The computation of the correlations by Pearson's tetrachoric _r_ shows the relationship between juvenile delinquency and deficiency among boys to be .16, P. E. .07, on the minimum estimate of deficiency. On the maximum estimate the correlation is .29, P. E. .05. In order to make a closer comparison between Goring's calculation and my own I have recalculated the correlation for his group on the assumption that 0.5% of the general male population were deficient and that 1.29% would be convicted felons of the type among which he found 10% to be deficient. This brings the minimum correlation for his figures to .59, P. E. .03. TABLE XIX FOUR-FOLD CORRELATION TABLE FOR JUVENILE DELINQUENCY AND DEFICIENCY IN MINNEAPOLIS (MINIMUM ESTIMATE). BOYS 8-16 YEARS OF AGE