Hi! We have run a linear regression model with 3 explanatory variables and get the output below. Does anyone know what type of test the anova model below does and why we get so different result in terms of significant variables by the two tables? Thanks! /Sara> summary(model)Call: lm(formula = log(HOBU) ~ Vole1 + Volelag + Year) Residuals: Min 1Q Median 3Q Max -0.757284 -0.166681 0.009478 0.181304 0.692916 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 80.041737 12.018726 6.660 1.40e-07 *** Vole1 0.005521 0.041626 0.133 0.8953 Volelag 0.033966 0.018392 1.847 0.0738 . Year -0.035927 0.006027 -5.961 1.08e-06 *** anova(model) Analysis of Variance Table Response: log(HOBU) Df Sum Sq Mean Sq F value Pr(>F) Vole1 1 1.7877 1.7877 13.1772 0.0009486 *** Volelag 1 0.5817 0.5817 4.2878 0.0462831 * Year 1 4.8205 4.8205 35.5323 1.082e-06 *** Residuals 33 4.4769 0.1357 [[alternative HTML version deleted]]
Hi! We have run a linear regression model with 3 explanatory variables and get the output below. Does anyone know what type of test the anova model below does and why we get so different result in terms of significant variables by the two tables? Thanks! /Sara> summary(model)Call: lm(formula = log(HOBU) ~ Vole1 + Volelag + Year) Residuals: Min 1Q Median 3Q Max -0.757284 -0.166681 0.009478 0.181304 0.692916 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 80.041737 12.018726 6.660 1.40e-07 *** Vole1 0.005521 0.041626 0.133 0.8953 Volelag 0.033966 0.018392 1.847 0.0738 . Year -0.035927 0.006027 -5.961 1.08e-06 *** anova(model) Analysis of Variance Table Response: log(HOBU) Df Sum Sq Mean Sq F value Pr(>F) Vole1 1 1.7877 1.7877 13.1772 0.0009486 *** Volelag 1 0.5817 0.5817 4.2878 0.0462831 * Year 1 4.8205 4.8205 35.5323 1.082e-06 *** Residuals 33 4.4769 0.1357 [[alternative HTML version deleted]] ______________________________________________ R-help at 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.
Hi Sara, As the help page for anova.lm says, "Specifying a single object gives a sequential analysis of variance table". That most likely also the answer to your second question. The anova function can be used to compare nested models, and this provides the flexibility to test arbitrary hypotheses, including all the ones given by different "types" of ANOVA tables. You may also find the Anova() function in the car package helpful. Best, Ista On Thu, May 12, 2011 at 2:37 AM, Sara Sj?stedt de Luna <sara.de.luna at math.umu.se> wrote:> Hi! > > We have run a linear regression model with 3 explanatory variables and get the output below. > Does anyone know what type of test the anova model below does and why we get so different result in terms of significant variables by the two tables? > > Thanks! > > /Sara > >> summary(model) > Call: > lm(formula = log(HOBU) ~ Vole1 + Volelag + Year) > Residuals: > ? ? ?Min ? ? ? ?1Q ? ?Median ? ? ? ?3Q ? ? ? Max > -0.757284 -0.166681 ?0.009478 ?0.181304 ?0.692916 > Coefficients: > ? ? ? ? ? ? Estimate Std. Error t value Pr(>|t|) > (Intercept) 80.041737 ?12.018726 ? 6.660 1.40e-07 *** > Vole1 ? ? ? ?0.005521 ? 0.041626 ? 0.133 ? 0.8953 > Volelag ? ? ?0.033966 ? 0.018392 ? 1.847 ? 0.0738 . > Year ? ? ? ?-0.035927 ? 0.006027 ?-5.961 1.08e-06 *** > > anova(model) > Analysis of Variance Table > Response: log(HOBU) > ? ? ? ? ?Df Sum Sq Mean Sq F value ? ?Pr(>F) > Vole1 ? ? ?1 1.7877 ?1.7877 13.1772 0.0009486 *** > Volelag ? ?1 0.5817 ?0.5817 ?4.2878 0.0462831 * > Year ? ? ? 1 4.8205 ?4.8205 35.5323 1.082e-06 *** > Residuals 33 4.4769 ?0.1357 > > > ? ? ? ?[[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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. >-- Ista Zahn Graduate student University of Rochester Department of Clinical and Social Psychology http://yourpsyche.org
Thanks a lot! Best, Sara -----Ursprungligt meddelande----- Fr?n: istazahn at gmail.com [mailto:istazahn at gmail.com] F?r Ista Zahn Skickat: den 12 maj 2011 16:46 Till: Sara Sj?stedt de Luna Kopia: r-help at r-project.org; Katie Andrle (katie.andrle at gmail.com) (katie.andrle at gmail.com) ?mne: Re: [R] lm and anova Hi Sara, As the help page for anova.lm says, "Specifying a single object gives a sequential analysis of variance table". That most likely also the answer to your second question. The anova function can be used to compare nested models, and this provides the flexibility to test arbitrary hypotheses, including all the ones given by different "types" of ANOVA tables. You may also find the Anova() function in the car package helpful. Best, Ista On Thu, May 12, 2011 at 2:37 AM, Sara Sj?stedt de Luna <sara.de.luna at math.umu.se> wrote:> Hi! > > We have run a linear regression model with 3 explanatory variables and get the output below. > Does anyone know what type of test the anova model below does and why we get so different result in terms of significant variables by the two tables? > > Thanks! > > /Sara > >> summary(model) > Call: > lm(formula = log(HOBU) ~ Vole1 + Volelag + Year) > Residuals: > ? ? ?Min ? ? ? ?1Q ? ?Median ? ? ? ?3Q ? ? ? Max > -0.757284 -0.166681 ?0.009478 ?0.181304 ?0.692916 > Coefficients: > ? ? ? ? ? ? Estimate Std. Error t value Pr(>|t|) > (Intercept) 80.041737 ?12.018726 ? 6.660 1.40e-07 *** > Vole1 ? ? ? ?0.005521 ? 0.041626 ? 0.133 ? 0.8953 Volelag ? ? ? > 0.033966 ? 0.018392 ? 1.847 ? 0.0738 . > Year ? ? ? ?-0.035927 ? 0.006027 ?-5.961 1.08e-06 *** > > anova(model) > Analysis of Variance Table > Response: log(HOBU) > ? ? ? ? ?Df Sum Sq Mean Sq F value ? ?Pr(>F) > Vole1 ? ? ?1 1.7877 ?1.7877 13.1772 0.0009486 *** Volelag ? ?1 0.5817 ? > 0.5817 ?4.2878 0.0462831 * Year ? ? ? 1 4.8205 ?4.8205 35.5323 > 1.082e-06 *** Residuals 33 4.4769 ?0.1357 > > > ? ? ? ?[[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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. >-- Ista Zahn Graduate student University of Rochester Department of Clinical and Social Psychology http://yourpsyche.org