Percentage of variability in county-level risk of preterm delivery explained by regression models that include varied combinations of variables or sets of counties.*
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*Percentages are based on R-squared values from the regression models. All models include 468 common counties unless indicated as otherwise.**Stepwise models were created using forward stepwise selection; see Table 1 for a list of variables included in each model.
创建时间：
2015-12-02
