FIG. 1.

Operative stone burden across the state of California and yearly precipitation and mean temperature. Each map shows the variables' relative magnitude for each county in California. The adjacent scatter plots compare the variable to county operative stone burden per 1000 persons. The fitted univariate regression line is also included on the scatter plots. With univariate modeling, only precipitation was significantly associated with county stone burden (p < 0.01). There was a trend toward significance for mean temperature (p = 0.10).