Thanks slre, I seem to be making some progress now.
Using a colon instead of an asterisk in the code really changes things. I had been getting residual SS and MS of zero. Which is ridiculous. Now I get much more plausible values. Also, When I used an asterisk instead of a colon It wouldn't give results for three way interactions. With colons it will. You are correct about plot being nested within treatment. There are six plots in each of 2 treatments. So, I guess I will have to perform a separate analysis to quantify the effect of treatment. Thanks again. Analysis of Variance Table Response: Combined.Rs Df Sum Sq Mean Sq F value Pr(>F) Combined.Trt 1 52.80 52.805 96.2601 < 2.2e-16 *** Combined.Plot 10 677.69 67.769 123.5380 < 2.2e-16 *** as.factor(Combined.Day) 16 2817.47 176.092 321.0041 < 2.2e-16 *** Combined.Trt:as.factor(Combined.Day) 16 47.82 2.989 5.4487 4.048e-10 *** Combined.Trt:Combined.Plot:as.factor(Combined.Day)80 455.42 5.693 10.3776 < 2.2e-16 *** Residuals 284 155.79 0.549 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 -- View this message in context: http://r.789695.n4.nabble.com/ANOVA-1-too-few-degrees-of-freedom-tp3493349p3499649.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.