How Birthrates Impact Demographics
"Among the 50 states plus Washington, D.C., white total fertility correlates at a remarkably strong 0.86 level with Bushs percentage of the 2004 vote. (In 2000, the correlation was 0.85.) In the social sciences, a correlation of 0.2 is considered low, 0.4 medium, and 0.6 high.
You could predict 74 percent of the variation in Bushs shares just from knowing each states white fertility rate. When the average fertility goes up by a tenth of a child, Bushs share normally goes up by 4.5 points."
Thanks to Laura Kranz