Re: [R] data summary and some automated t.tests.

2009-05-17 Thread David Freedman
You might want to try using a non-parametric test, such as wilcox.test. How about some modification of the following: d=data.frame(grp=rep(1:2,e=5),replicate(10,rnorm(100))); head(d) lapply(d[,-1],function(.column)wilcox.test(.column~grp,data=d)) David Freedman stephen sefick wrote: > > Up a

Re: [R] data summary and some automated t.tests.

2009-05-16 Thread stephen sefick
Up and down are the treatments. These are replicates within date for percent cover of habiat. This is habitat data for a stream restoration - up is the unrestored and dn is the restored. I have looked at the density plots and they do not look gaussian - you are absolutely right. Even log(n+1) t

Re: [R] data summary and some automated t.tests.

2009-05-16 Thread Uwe Ligges
stephen sefick wrote: I would like to preform a t.test to each of the measured variables (sand.silt etc.) I am a big fan of applying t.test()s, but in this case: Are you really sure? The integers and particularly boxplot(x) do not indicate very well that the variables are somehow close to G

[R] data summary and some automated t.tests.

2009-05-15 Thread stephen sefick
I would like to preform a t.test to each of the measured variables (sand.silt etc.) with a mean and sd for each of the treatments (up or down), and out put this as a table I am having a hard time starting- maybe it is to close to lunch. Any suggestions would be greatly appreciated. Stephen S