The influence of the economic factor on infant mortality among the babies born prior to 1911 can not be determined with exactness, as no inquiry was made concerning earnings of the father when the other children were born. But it is believed that his earnings during the year following the birth of the 1911 baby can be regarded as an index of the economic standing of the family for some time past. In individual cases, of course, revolutionary changes in the family’s income may have occurred, but for the great mass of people in the group considered it is not likely that within such a short space of time as that covered by the child-bearing period of the women considered—most of whom had not had numerous pregnancies—marked changes had taken place. If these known earnings are accepted as an index, the following variations are found to occur in the infant mortality rate for all the babies of whom a record was secured: TABLE 42.—INFANT MORTALITY RATE FOR ALL CHILDREN OF MARRIED MOTHERS INCLUDED IN THIS INVESTIGATION, DISTRIBUTED ACCORDING TO THE FATHER’S EARNINGS. ══════════════════════════════════════════╤════════════════════════════ FATHER’S ANNUAL EARNINGS. │ Infant mortality rate. ──────────────────────────────────────────┼──────────────────────────── Under $521 │ 197.3 $521 to $624 │ 193.1 $625 to $779 │ 163.1 $780 to $899 │ 168.4 $900 to $1,199 │ 142.2 $1,200 and over │ 102.2 ──────────────────────────────────────────┴──────────────────────────── The infant mortality rate for the babies whose fathers earn under $521 is almost twice as great as for those born into families in the most prosperous group. These figures strengthen the conclusion reached in the study of the babies born in 1911, namely that the economic factor is of far-reaching importance in determining the baby’s chance of life. TABLE V.—DISTRIBUTION OF LIVE BIRTHS AND OF DEATHS DURING FIRST YEAR, ACCORDING TO NUMBER OF PERSONS AND NUMBER OF ROOMS PER FAMILY.