Hello, I have a simple question about using the aov function syntax (ie. * + or :) for the interaction of 2 factors. I have read the help files, and researched other sites, and have included my source files. My goal is to measure the signifigance of the interaction between population and condition (aka. population:condition). I can't seem to figure it out.
1. In the first example the significance of population:condition works with the "allData" but not with the "studentData." Can you please explain why it fails and how I can fix it? 2. In the second example I can get the measure the significance of population:condition with 2 different methods, but I get 2 different results (using the "allData" source). Can you please explain why these Pr(>F) values are different? Thank you so much for your help!! Sincerely, Dave Deriso UCSD Psychiatry #Example 1 ---------------------------COPY & PASTE THE FOLLOWING #import the data allDataSource="http://files.davidderiso.com/r/allData.data"; allData.import=read.table(allDataSource,header=T) studentDataSource="http://files.davidderiso.com/r/allData.data"; studentData.import=read.table(studentDataSource,header=T) #aov for allData WORKS allData.integral.aov = aov(integral~population*condition, data=allData.import) summary(allData.integral.aov) #aov for studentData DOES NOT GIVE Pr(>F) of population:condition studentData.integral.aov = aov(integral~population*condition, data=studentData.import) summary(studentData.integral.aov) #Example 2 ---------------------------COPY & PASTE THE FOLLOWING #population:condition has a Pr(>F) of 0.96372 allData.integral.aov = aov(integral~population*condition, data=allData.import) summary(allData.integral.aov) #population:condition has a Pr(>F) of 1.070e-06 *** allData.integral.aov = aov(integral~population:condition, data=allData.import) summary(allData.integral.aov) [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
