Speaking Stata: The Protean Quantile Plot

Abstract

Quantile plots showing by default ordered values versus cumulative probabilities are both well known and also often neglected, considering their major advantages. Their flexibility and power is emphasized by using the qplot program to show several variants on the standard form, making full use of options for reverse, ranked, and transformed scales and for superimposing and juxtaposing quantile traces. Examples are drawn from the analysis of species abundance data in ecology. A revised version of qplot is formally released with this column. Distribution plots in which the axes are interchanged are also discussed briefly, in conjunction with a revised version of distplot, also released now.