Samuel, use o panel.rect(), veja histogram( ~ height | voice.part, prob=T, data = singer, xlab = "Height (inches)", type = "density", panel = function(x, ...) { * panel.rect(40, 0, qnorm(0.25, mean=mean(x), sd=sd(x)), 1, col="gray90") * panel.histogram(x, ...) panel.mathdensity(dmath = dnorm, col = "black", args = list(mean=mean(x),sd=sd(x))) panel.abline(v=qnorm(0.25, mean=mean(x), sd=sd(x)), lty=2, col='blue') panel.abline(v=qnorm(0.75, mean=mean(x), sd=sd(x)), lty=2, col='blue') } ) À disposição. Walmes. ========================================================================== Walmes Marques Zeviani LEG (Laboratório de Estatística e Geoinformação, 25.450418 S, 49.231759 W) Departamento de Estatística - Universidade Federal do Paraná fone: (+55) 41 3361 3573 VoIP: (3361 3600) 1053 1173 e-mail: walmes@ufpr.br twitter: @walmeszeviani homepage: http://www.leg.ufpr.br/~walmes linux user number: 531218 ==========================================================================