search for: jfc10816

Hi dear listers Do you know how to made a mean by one or more categorical variables? I can do that quite easy on SAS by in R I just can't do it E.g. Some fishes Sex Lenght male 15 fema 20 fema 17 fema 19 male 18 So the idea is mean(Lenght) by sex, in order to have sex: Male mean=XX Sex: Fema mean=YY In this case is quite easy to do it by a loop, but I have a huge DB so is not an

Hi, I'm traing to use the GLM to find tendences on my data. E.G. Data.frame: MyData Len Zone Year 12 1 2002 21 1 2003 32 1 2004 32 2 2002 32 2 2003 31 2 2004 3 3 2002 4 3 2003 3 3 2004 32 4 2002 4 4 2003 5 4 2004 I want toi fing tendences on the len, if they change over the year (the anova say yes), but I wan't to include the zone as a Random effect So, I have something like this: