Hello, I am a new user to R and have a(proabably very basic) question relating to a boxplot with eleven sites in a river system where i measured Chlorophyll a concentrations. The eleven sites are made up of three sites above a point source pollution site; three sites below this pollution source and five sites in a different unaffected river. The following code is for a simple plot of the data boxplot(Chl~Site,data=p,col="slategrey", boxwex=0.75,xlab="Site",ylim=c(0,250)) mtext(expression("Chlorophyll a" (mg/m^2)),side=2,line=2.75,cex=0.7) The question is: 1) In my data sheet I have the sites grouped together (i.e. above pollution, below and unaffected), but the default setting in R seems to place these alphabetically on the x-axis rather than in the order I have entered into the spreadsheet. How to i correct this? Many thanks, Phil [[alternative HTML version deleted]]