Boxplot depicting the R² from separate simple linear regressions for the effect of the absolute percent difference in σ_PQL and σ_QUAD on the absolute percent bias in σ_QUAD or σ_PQL, respectively, overall and by data generation parameters.

<p>Median (interquartile range) of the R² is the center of the box, box edges are the 25^th and 75^th percentile respectively, ends of the dashed lines are the 10^th and 90^th percentile, respectively.