On Apr 1, 2011, at 11:24 AM, Yan Jiao wrote:
boxplot(c(1:3),c(4:6),c(5:8))
df <- structure(list(grp = c(1, 1, 1, 2, 2, 2, 3, 3, 3, 3), val = c(1L, 2L, 3L, 4L, 5L, 6L, 5L, 6L, 7L, 8L)), .Names = c("grp", "val"), row.names = c(NA, -10L), class = "data.frame") boxplot(val~grp,data=df) lm(val~grp, data=df) #Call: #lm(formula = val ~ grp, data = df) #Coefficients: #(Intercept) grp # 0.04348 2.21739 ?abline abline(reg=lm(val~grp, data=df) ) -- David Winsemius, MD West Hartford, CT ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.