Dear list members, I have a set of soil samples tested for one Element taken at 3 different depths (respectively at depth A, B and C) on a transect. I want to determine whether the results for the different layers (depths) are comparable.
From the literature I found that 2 tests can to be employed:
1) An extension of ANOVA that accounts for a blocking effect (different samples taken at same position) = ANOVA (two way) 2) Non parametric equivalent of ANOVA with blocking the Friedman test In both case, I got stuck. In the case of Friedman ( http://stat.ethz.ch/R-manual/R-patched/library/stats/html/friedman.test.html) the example is given with a matrix and so far I was only dealing with data.frame. I didnt figure out how to transform my data into a matrix or if the data frame can be used directly. With the two way ANOVA (http://cran.r-project.org/web/packages/car/car.pdf(p.11)), I did not managed to figure out which argument to use for the linear model (lm). If someone is interested to give me a hand find attached the surveys data at different depth.
Mit freundlichen Gr??en / Kind regards / Meilleures Salutations Eric B?ker Project Manager Eiseb Prospecting and Mining (Pty)Ltd Gobabis, Namibia <eric at eiseb.com> -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://stat.ethz.ch/pipermail/r-sig-geo/attachments/20111118/bc666683/attachment.html> -------------- next part -------------- A non-text attachment was scrubbed... Name: soil.csv Type: text/csv Size: 2268 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-sig-geo/attachments/20111118/bc666683/attachment.bin>