In contrast, the Florida population is probably not nearly as equal, regarding these characteristics, as the Rawlings population across racial lines. It may be that black women and white women with birth intervals of 9 months or more would have similar LBW percentages if they had similar income and prenatal care levels. The graph shows the low birth rates for the Florida data for black and white births in relation to the interval calculated as explained above. In an effort to smooth the curve a 3 month moving percentage is used. Table 5 gives the number and percent of births for black and white mothers across the 4 categories of birth interval.
Black women are therefore more likely to have shorter birth intervals.
It is evident that some of the differences in LBW percentages between black and white births are due to the shorter average birth intervals for black births. Table 6 is an attempt to quantify this. In table 6 the black births are re-distributed across the 4 birth interval categories based on the percentages in these categories for white births. The LBW percent for black births in each category is then applied to the adjusted black births to get the adjusted black LBW births of 2318. This is in contrast to the actual black LBW births of 2367.