As an agronomist, sometimes i need to perform statistical analisys on "weird" field data, like 3 or 4 level split plot design. I've read both the help of the program, some books and manual about S and "Venables/Ripley, Modern Applied Statistics with S", but i still have problems in (i suppose) formulae sintax. I'm trying to perform AOV, as explained in "Random and Mixed Effects", chapter 10, V./R., on a data set i collected on turf root density under different turf species, substrates, fertilisation and sampling depht. ..and 12 replicates So, on a general formulation, i have a response factor, say, Roots, treatmens T1, T2, T3 and T4, and Rep replicates, organized on a four levels split plot design. I have an old gwbasic program, simple and time tested, that can calculate the analisys of variance of 3 levels split plot experiment, and when i compare his output whit the results obtained with R, i find that i (probably) fail to define the nesting effect of the split plot design. Can anyone suggest me how to specify the response and error term in the aov formula? Thank in advance Gruppo Tappeti Erbosi Dipartimento Produzione Vegetale Universit? degli Studi della Tuscia Viterbo - Italy + 39 0761 357541 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._