Most likely your combined.trt is linearly dependent on the combined.plot factor. Try
Anova.Trt.D.M.T.Pr.Model <- aov(Combined.Rs ~ as.factor(Combined.Plot) ..... and see if combined.plot now has the 11 df you are anticipating. Rich On Tue, May 3, 2011 at 3:37 PM, Rovinpiper <david.j.mee...@gmail.com> wrote: > I'm running an ANOVA on some data for respiration in a forest. I am having > a > problem with my degrees of freedom. For one of my variables I get one fewer > degrees of freedom than I should. > > I have 12 plots and I therefore expected 11 degrees of freedom, but instead > I got 10. > > Any ideas? > > I have some code and output below: > > > > class(Combined.Plot) > [1] "character" > > > levels(as.factor(Combined.Plot)) > [1] "60m" "A1" "B1" "B3" "B4" "C5" "C9" "D2" "D9" "F60m" > "F8" "Q7" > > > nlevels(as.factor(Combined.Plot)) > [1] 12 > > > Anova.Trt.D.M.T.Pr.Model <- aov(Combined.Rs~Combined.Trt + > > as.factor(Combined.Plot) + as.factor(Combined.Day) + > > Combined.Trt*as.factor(Combined.Day) + > > Combined.Plot*as.factor(Combined.Day)) > > Warning message: > In model.matrix.default(mt, mf, contrasts) : > variable 'Combined.Plot' converted to a factor > > > summary(Anova.Trt.D.M.T.Pr.Model) > Df Sum Sq > Mean Sq F value Pr(>F) > > Combined.Trt 1 52.80 > 52.805 2.0186e+30 < 2.2e-16 *** > as.factor(Combined.Plot) 10 677.69 67.769 > 2.5907e+30 < 2.2e-16 *** > as.factor(Combined.Day) 16 2817.47 176.092 > 6.7317e+30 < 2.2e-16 *** > Combined.Trt:as.factor(Combined.Day) 16 47.82 2.989 > 1.1426e+29 < 2.2e-16 *** > as.factor(Combined.Day):Combined.Plot 160 611.21 3.820 1.4604e+29 < > 2.2e-16 *** > > Residuals 204 0.00 > 0.000 > > --- > > 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-tp3493349p3493349.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. > [[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.
