TABLE 3.

Comparing the Proportion with Breast Stage 2+ by Age Between BCERP Puberty Study Cross-Sectional Equivalent Data and PROS⁹

Age Group	Black						White
	PROS		BCERP Puberty Studya				PROSc		BCERP Puberty Studya
	Total No. of Girls	Percent at Breast Stage 2+	Total No. of Girls	Percent at Breast Stage 2+	χ Squareb	P Valueb	Total No. of Girls	Percent at Breast Stage 2+	Total No. of Girls	Percent at Breast Stage 2+	χ Squareb	P Valueb
6.0–6.9	126	6	100	18	7.43	.006	1506	3	77	4	0.24	.496
7.0–7.9	136	15	257	22	2.28	.131	1128	5	320	10	11.07	.001
8.0–8.9	143	38	294	38	0.02	.892	1334	11	363	21	29.39	<.0001
9.0–9.9	115	63	282	62	0.00	.971	1067	32	379	42	12.50	.000
10.0–10.9	112	80	269	87	2.73	.098	1153	62	340	71	10.01	.002
11.0–11.9	126	96	190	96	0.02	.999	1104	85	244	92	8.15	.004
12.0–12.9	91	99	133	99	0.07	.999	923	96	156	98	1.63	.256

^aEvery B visit in the BCERP Puberty Study was treated as if it were a separate girl; missing visits or visits with refused Tanner staging not included.

^bFisher’s Exact Test used where cell frequency is ≤5.

^cPROS did not separate Hispanic and Non-Hispanic white subjects; the BCERP Puberty Study did.