Matteo, I think that in the gregmisc package, there is barplot2 which is an enhancement to barplot that allows error bars. You might look into that option, also.
Sean On 5/21/04 11:15 AM, "Spencer Graves" <[EMAIL PROTECTED]> wrote: >> DF <- data.frame(mean=c(1.25, 2.65, 3.45), sd=c(.35, .65, .5), > + row.names=letters[1:3]) >> plot(1:3, DF$mean, ylim=range(DF$mean-2*DF$sd, DF$mean+2*DF$sd)) >> segments(1:3, DF$mean-2*DF$sd, 1:3, DF$mean+2*DF$sd) > > hope this helps. spencer graves > > Matteo Vidali wrote: > >> I need some help for a curious question of a friend of mine. >> She usually does some experiments (3-5 repeats for each exp) and then she >> calculates mean and standard deviation. >> In microsoft excel she writes something like the following >> >> sample mean sd >> a 1.25 0.35 >> b 2.65 0.65 >> c 3.45 0.50 >> >> She can do a vertical barplot graph just giving mean value and specifying >> the standard deviation value for each bar in the graph. >> >> My friend wants to know if it is possible to do the same with R. She has >> tried also with Open Office and seen that in that program you can plot mean >> values as bars but it is not possible to specify a different sd for each >> bar 'cause the program, if you ask to put the standard deviation, calculates >> a common sd using the mean values. >> I was not able to give her an answer for the barplot function in R. I have >> just said to her that it is likely due to the fact that using a barplot >> graph to plot mean and standard deviation values it is non a good practice, >> since the height (or the area) of bars should represent frequency and that >> putting a standard deviation in that way it is at least quite confusing for >> the reader to interpret the graph. Some scientific journal revisors >> discourage this practice. She should instead use a boxplot or just plotting >> the different repetition values for each sample as points and add a linea >> indicating the mean. >> But if this is correct why in some programs like open office you can plot >> bars with a common standard deviation???? when will you need this last type >> of graph? >> >> any suggestion? any help? >> thanks in advance >> Matteo >> >> ______________________________________________ >> [EMAIL PROTECTED] mailing list >> https://www.stat.math.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html >> >> > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
