Hi, 

Can anyone help with plotting vertical error bars on a bar graph. 

I have tried following examples online and in the big R book and writing my own function but I have been unsuccessful and don’t really have an understanding of what it is I am doing. I have calculated my standard errors so basically just need to draw the bars on the graph but just don’t have a clue!!!

I don’t even know what information people will need to help me......

The code for my graph is:

barplot(tapply(Sporangia,list(Host,Isolate),mean),xlab="Isolate",ylab="Mean Sporangia per Needle",col=c("grey39","grey64","grey89"),beside=T)
col=c("grey39","grey64","grey89")
legend("topright",inset=.05,title="Host",c("European Larch","Hybrid Larch","Japanese Larch"),fill=col,horiz=FALSE)

Any help would be greatly appreciated, 

Anna


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