Hi You probably could get better answer from experts but it has something to do with contrasts.
?contrasts Number 44.556 is mean for wool A and tension L and this is the level to which every other level is compared. Cheers Petr > -----Original Message----- > From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Ashim > Kapoor > Sent: Thursday, December 1, 2016 2:48 PM > To: r-help@r-project.org > Subject: [R] Interpreting summary.lm for a 2 factor anova > > Dear all, > > Here is a small example : - > > > model <- aov(breaks ~ wool * tension, data = warpbreaks) > > summary.lm(model) > > Call: > aov(formula = breaks ~ wool * tension, data = warpbreaks) > > Residuals: > Min 1Q Median 3Q Max > -19.5556 -6.8889 -0.6667 7.1944 25.4444 > > Coefficients: > Estimate Std. Error t value Pr(>|t|) > (Intercept) 44.556 3.647 12.218 2.43e-16 *** > woolB -16.333 5.157 -3.167 0.002677 ** > tensionM -20.556 5.157 -3.986 0.000228 *** > tensionH -20.000 5.157 -3.878 0.000320 *** > woolB:tensionM 21.111 7.294 2.895 0.005698 ** > woolB:tensionH 10.556 7.294 1.447 0.154327 > --- > Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 > > Residual standard error: 10.94 on 48 degrees of freedom > Multiple R-squared: 0.3778, Adjusted R-squared: 0.3129 > F-statistic: 5.828 on 5 and 48 DF, p-value: 0.0002772 > > > model.tables(model,"e") > Tables of effects > > wool > wool > A B > 2.8889 -2.8889 > > tension > tension > L M H > 8.241 -1.759 -6.481 > > wool:tension > tension > wool L M H > A 5.278 -5.278 0.000 > B -5.278 5.278 0.000 > > > > model.tables(model,"m") > Tables of means > Grand mean > > 28.14815 > > wool > wool > A B > 31.037 25.259 > > tension > tension > L M H > 36.39 26.39 21.67 > > wool:tension > tension > wool L M H > A 44.56 24.00 24.56 > B 28.22 28.78 18.78 > > > > I don't follow the output of summary.lm. I understand the output of > model.tables for effects and means. For instance what does 44.556 > represent ? Is it the grand average ? The grand mean is 28.14815. Can > someone help me understand the output of summary.lm ? > > Best Regards, > Ashim > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. ________________________________ Tento e-mail a jakékoliv k němu připojené dokumenty jsou důvěrné a jsou určeny pouze jeho adresátům. Jestliže jste obdržel(a) tento e-mail omylem, informujte laskavě neprodleně jeho odesílatele. Obsah tohoto emailu i s přílohami a jeho kopie vymažte ze svého systému. 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