│ School │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ GIRLS │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │Ordinary │14.0│ 5.9│ 1.8│ 0.│ │ │ │ │ │ │ Pupils │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │Ordinary │15.8│32.6│20.0│ 8.4│9.4│1.1│2.1│2.1│ │ │ Delinquents│ │ │ │ │ │ │ │ │ │ └─────────────┴────┴────┴────┴────┴───┴───┴───┴───┴───┘ [Illustration: FIG. 2. _School Retardation of Minneapolis Delinquents Compared With Elementary School Boys._] In the Minneapolis group of elementary school children it will be found that there is about as much chance of a child being in either of the two most common ages for a grade. Among the boys, for example, 36% were in the series represented by age 6 in the first grade, 7 in the second grade, 8 in the third grade, etc., while 30% were in the series represented by one year older for each grade. It is, therefore, reasonable to regard either 6 or 7 as a satisfactory age in the first grade, 7 or 8 in the second, when one estimates the amount of retardation in this group. The allowance of two ages as satisfactory for a grade is in conformity with the practise of Strayer (_189_). The necessity of taking these ages at either the beginning or the end of the school year, and not merely “in the grade,” is emphasized by the report of the New York City Committee on School Inquiry (_72_). Ayres (_71_) also considers only those pupils over-age who are over 7 in the first grade, 8 in the second, etc., so that this may be regarded as fairly well established as a standard for measuring the retardation in school position of groups of children. The summary of results in Table XIII shows that 70% of the ordinary delinquent boys were retarded in school position as compared with 27% among the Minneapolis boys in the elementary schools, 91% of the ordinary delinquent girls as compared with 23% of the Minneapolis girls of these schools. When one compares the age distribution of the delinquent groups, given in Table XIII with that of the Minneapolis school children in Table XII, it is clear that an allowance should be made for the much larger proportion of older children in the delinquent groups. This may be done by determining the percentage retarded at each age and in each group and then calculating indices of retardation by weighting the percentage retarded at each age in the proportion to the number of delinquents at that age. Table XIV gives these results for the ages 8 to 15 inclusive.