Dear R, I tried to find the definition of the ncp parameter for the F-distribution in the manual. Somehow, I could not find it in the documentation. For some reasons the density F function does not contain the ncp parameter. I can manage this by differentiating numerically the cumulative one, or am I overlooking something. My purpose is to demonstrate to the students the central F ( H0) and noncentral F (Ha under some assumed scenario). The implementation appears to be different from the Neter, Kutner, Nachtsheim and Wasserman 1996 on linear models. thanks and kind regards, Guido Wyseure FLTBW/ Facultaire Didaktiek /Office LI 91.21 Kasteelpark Arenberg 21 3001 Heverlee (Leuven) tel +32/16/3 29661 fax 32/16/3 21964 Http://www.agr.kuleuven.ac.be -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- 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 _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._