Quantile Regression Estimation of Treatment Effects. In the above Figure, quantile regression is used to estimate treatment effects across a range of survival time quantiles (τ = 0.10, …, 0.90). For a given quantile τ (horizontal axis), the vertical axis represents the percent increase in survivorship of Mediterranean fruit flies associated with an experimental treatment. In part (A), results for the PappA(−/−) treatment are shown, and in part (B), results for the bIrs2(+/−) treatment are shown. In each plot, the middle line represents the calculated effect of experimental treatments at each survival time quantile, while the upper and lower lines outline a 95% confidence region. It is clear that in Part A, treatment effects don’t change with respect to the specific quantile. However, in Part B, the treatment effects decrease as the quantile increases.Reference: Swindell (2009) . Reproduced with permission.
Willke et al. BMC Medical Research Methodology 2012 12:185 doi:10.1186/1471-2288-12-185