Awesome, that's what I was looking for. I have two additional questions: (1) What can I do if the variables are of different lengths? (2) How do I update the formula if I want to control for more than one variable.
Let's take the following example: x <- c(1,20,14,7,9) y <- c(5,6,7,9,10,11) z <- c(13,27,16,5,4,17,20) a <- c(4,6,7,1) xres <- residuals(lm(x ~ z)) yres <- residuals(lm(y ~ z)) cor(xres, yres) ct <- cor.test(xres, yres) ct$estimate ct$p.value How do I update the above formula to: (1) take into account that the variables are of different lengths? I get an error when calculating the residuals. (2) control for z and a (i.e., more than one variable)? Thanks so much for your help. Peter Ehlers wrote: > > > dadrivr wrote: >> I'm trying to write code to calculate partial correlations (along with >> p-values). I'm new to R, and I don't know how to do this. I have >> searched >> and come across different functions, but I haven't been able to get any >> of >> them to work (for example, pcor and pcor.test from the ggm package). >> >> In the following example, I am trying to compute the correlation between >> x >> and y, while controlling for z (partial correlation): >> >> x <- c(1,20,14,7,9) >> y <- c(5,6,7,9,10) >> z <- c(13,27,16,5,4) >> >> What function can I append to this to find this partial correlation? >> Many >> thanks! > > I'm not sure what you need, but does this give you what > you want: > > xres <- residuals(lm(x ~ z)) > yres <- residuals(lm(y ~ z)) > cor(xres, yres) > # [1] 0.9778857 > > or > > ct <- cor.test(xres, yres) > ct$estimate # 0.9978857 > ct$p.value # 0.003934582 > > -Peter Ehlers > >> >> > > ______________________________________________ > 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. > > -- View this message in context: http://old.nabble.com/Partial-correlations-and-p-values-tp26308463p26312873.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.