Re: [R] Rsquared for anova

From: Dorien Herremans <dorien.herremans_at_ua.ac.be>
Date: Mon, 18 Apr 2011 15:20:29 +0200

Omg Dieter, thanks so much... I just had to q() and R... that solved it :-) excellent! finally got the R2 :-)

On 18 April 2011 15:12, Ben Bolker <bbolker_at_gmail.com> wrote:
> Dorien Herremans <dorien.herremans <at> ua.ac.be> writes:
>
>>
>> Thanks Dieter,
>>
>> Even if I use lm(), I get the following output:
>>
>> > summary(fit)
>>              Df  Sum Sq Mean Sq F value    Pr(>F)
>> nh1            1   324.0  323.99  139.13 < 2.2e-16 ***
>> nh2            1   723.1  723.12  310.53 < 2.2e-16 ***
>> nh3            1  1794.2 1794.21  770.49 < 2.2e-16 ***
>> Residuals   4604 10721.2    2.33
>> ---
>> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’
>>
>> no R squared to be found.
>>
>
>  Really ??
>
>  When I run the example in ?lm I get:
>
>> summary(lm.D9)
>
> Call:
> lm(formula = weight ~ group)
>
> Residuals:
>    Min      1Q  Median      3Q     Max
> -1.0710 -0.4938  0.0685  0.2462  1.3690
>
> Coefficients:
>            Estimate Std. Error t value Pr(>|t|)
> (Intercept)   5.0320     0.2202  22.850 9.55e-15 ***
> groupTrt     -0.3710     0.3114  -1.191    0.249
> ---
> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
>
> Residual standard error: 0.6964 on 18 degrees of freedom
> Multiple R-squared: 0.07308,    Adjusted R-squared: 0.02158
> F-statistic: 1.419 on 1 and 18 DF,  p-value: 0.249
>
>    Note the last three lines.  I would be shocked if there
> weren't a similar set of information in your output ...
>
>  Your output looks like the result of summary(aov(...))
>
>
>> Another strange thing. I did the same calculations in SPSS and got
>> different results, among others, higher p values. lm() and aov() just
>> do linear regressions (anova) right? I tried with the same factorial
>> variables (without interaction effects to test).
>
>   There are a lot of things that could be different. Are
> you treating factors (categorical predictors) as numeric by
> accident?
>
>>
>> Thanks!
>>
>> On 15 April 2011 18:07, Dieter Menne <dieter.menne <at> menne-biomed.de> wrote:
>> >
>> > dorien wrote:
>> >>
>> >> I calculate an anova test in the following way:
>> >>
>> >> ... aov example
>> >>
>> >> I want to check the fit of the model with Rsquared
>> >>
>> >
>> > Try summary(lm(...)) instead.
>> >
>> > Dieter
>> >
>> >
>> >
>> > --
>> > View this message in context:
> http://r.789695.n4.nabble.com/Rsquared-for-anova-tp3452399p3452434.html
>> > Sent from the R help mailing list archive at Nabble.com.
>> >
>> > ______________________________________________
>> > 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.
>> >
>>
>> --
>> Dorien Herremans
>>
>> Department of Environment, Technology and Technology Management
>> Faculty of Applied Economics
>> University of Antwerp
>>
>> B.513
>> Prinsstraat 13
>> 2000 Antwerp
>> Belgium
>> +32 3 265 41 25
>>
>
> ______________________________________________
> 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.
>

-- 
Dorien Herremans

Department of Environment, Technology and Technology Management
Faculty of Applied Economics
University of Antwerp

B.513
Prinsstraat 13
2000 Antwerp
Belgium
+32 3 265 41 25

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