Introduction

If families or households are grouped by their size, as measured by number of persons, the common finding is that the larger families or households show a larger income per unit. But if the family or household income is divided by the number of members, per person income is larger in the smaller families or households and smaller in the larger units. An illustration of the positive association between the size of family and income per family, and of the negative association between size of family and family income per person, is provided in Table 11.1 below for the United States in 1969–70 (money income is for calendar 1969 and size of family is shown for March 1970). Income per family ranged from a low of $8.8 thousand for a family of two persons to $12.2 thousand for a family of five or six persons and $11.5 thousand for a family of seven persons or more. Family income per person declined sharply from $4.4 thousand for families of two persons to $1.4 thousand for families of seven or more.

Larger families or households usually contain a higher proportion of children among the members and a smaller proportion of adults than the smaller families or households. It follows that children are more concentrated than adults in larger families or households and, consequently, in families or households with lower per person income.