Table 3.

Phase I stratification for the North Carolina low birth weight data, with S stratifying births according to county-specific percentage of non-white births and of male births.

	County-specific percentage non-white births
	0.0%–15.0%	15.0%–31.0%	31.1%–46.0%	46.1%–61.0%	61.1%–76.0%
Y = 0	49,130	89,341	69,248	6406	6491
Y = 1	4131	8455	7153	817	937
	County-specific percentage male births
	45.0%–47.0%	47.1%–50.0%	50.1%–52.0%	52.1%–54.0%	54.1%–57.0%
Y = 0	1440	20,290	155,846	33,918	4991
Y = 1	175	2069	15,395	3321	533