Regression intercepts for PGLS and OLS regression with fixed slope 0.75 from Werner and Griebeler [3].

<p>The values of the regression intercept for PGLS and OLS regression are given in Tables 2 and S3 in [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192912#pone.0192912.ref003" target="_blank">3</a>]. Here they are plotted against one another to show their relationship; error bars show the 95% confidence intervals. If the two methods gave the identical intercept they would like on the line <i>y</i> = <i>x</i> (<i>black</i>, <i>dashed</i>), and this lies within the PGLS 95% confidence interval for every group except precocial birds (which are close). The red line is the result of a simple linear fit, with parameters given in the legend. It shows that taken across all groups the primary difference between PGLS and OLS coefficients is a constant offset.