Hi everyone, I have a question about calculating r-squared in R. I have tried searching the archives and couldn't find what I was looking for - but apologies if there is somewhere I can find this...
I carried out a droughting experiment to test plant competition under limited water. I had: - 7 different levels of watering treatment (1 -7 - from most watered to least watered/) - 15 replicates at each level. Soil moisture readings were taken 4 times throughout the experiment (so I have 105 readings for each of the 4 times) and I now want to check that there was a significant decrease in soil moisture as I decreased the watering frequency, i.e. watering level 7 showed lower soil moisture units than level 1. I have carried out a repeated measures anova as follows (where block is which time the reading was taken: 1,2,3 or 4): model1<-aov(soilmoisture~wateringlevel+Error(block/wateringlevel)) I then plotted (soilmoisture~wateringlevel) and fitted a regression line: lm1<-lm(soilmoisture~wateringlevel) abline(lm1,lty=1) Here are my questions: 1) Is the repeated measures anova I have entered correct to tell me if there is a significant difference in my watering levels? 2) How do I calculate r2 value to show much variation my watering level explains? - and then put this figure on my plot? Thank you - and again apologies if this is a too-basic question - (I am a real stats and R beginner). Please let me know if I need to provide any more detail! Sarah [[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.