search for: huitema

Dear R help contributers, I have several x,y scatter plots and I would like to plot them slightly offset, similar to: http://www.mathworks.com/matlabcentral/fx_files/24368/2/content/style4.jpg I've looked all over for this answer with no luck. Just a function name or previous example would probably be enough for me to figure it out. Thank-you in advance, Carly

Hello R-help list, I would really appreciate help with my factoring problem. My generated data is this: df <- expand.grid(T=seq(10,80, by=5), conc=rep(c(1, 3, 7), 2)) df$curve <- as.factor(rep(1:6, each=length(seq(10,80, by=5)))) df$counts <- 3*df$T/df$conc + rnorm(df$T,0,2) plot(counts~T, df) What I would like to do add a new column to the dataframe of zeroed data (say

...t then the test for group differences only tests for differences in intercept. This is in many cases not what was initially intended. Instead, what one wants is perhaps to determine values of the covariate at which the groups differ. I??ve seen a description of the Johnson-Neyman procedure (in Huitema (1980)), which allows to determine the so called regions of nonsignificance, which sounds a lot like what I want. The problem is I have very seldom seen it used (at least in my field of work), but unequal slopes is a common problem. (Searching the R-help archives, however, didn??t give me a sin...