[R] Anova(car) SS digits

Tyler Smith tyler.smith at mail.mcgill.ca
Thu Nov 29 20:07:02 CET 2007


Hi,

When I use Anova(car) to produce type III SS, 'Sum Sq' is reported in
integers:

> Anova(bot.lm3, type ="III")
Anova Table (Type III tests)

Response: bottemp
                         Sum Sq  Df    F value  Pr(>F)
(Intercept)               45295   1 29436.4440 < 2e-16
fungroup                      3   2     0.8259 0.44006
numsp.fun                    11   2     3.4503 0.03460
block                       419   4    68.0017 < 2e-16
fungroup:numsp.fun            6   4     1.0317 0.39340
fungroup:block                9   8     0.7429 0.65346
numsp.fun:block              12   8     0.9501 0.47795
fungroup:numsp.fun:block     27  16     1.0920 0.36882
Residuals                   205 133                   

I have tried specifying digits = 7 in the call to Anova, but that
doesn't change anything. The output from another stats program for the
same data confirms that the ouptut above is correct, but is rounded to
the nearest integer. The dataset is too large to post here, but I can
confirm that I get the expected results from the examples in ?Anova,
as well as for type = 'II' on my own data. This output, and relevant
options() and sessionInfo are pasted below. What am I doing wrong?

Thanks,

Tyler

>      mod <- lm(conformity ~ fcategory*partner.status, data=Moore, 
+        contrasts=list(fcategory=contr.sum, partner.status=contr.sum))
>      Anova(mod)
Anova Table (Type II tests)

Response: conformity
                         Sum Sq Df F value   Pr(>F)
fcategory                 11.61  2  0.2770 0.759564
partner.status           212.21  1 10.1207 0.002874
fcategory:partner.status 175.49  2  4.1846 0.022572
Residuals                817.76 39                 
>      Anova(mod, type="III")
Anova Table (Type III tests)

Response: conformity
                         Sum Sq Df  F value    Pr(>F)
(Intercept)              5752.8  1 274.3592 < 2.2e-16
fcategory                  36.0  2   0.8589  0.431492
partner.status            239.6  1  11.4250  0.001657
fcategory:partner.status  175.5  2   4.1846  0.022572
Residuals                 817.8 39                   

> Anova(bot.lm3, type ="II")
Anova Table (Type II tests)

Response: bottemp
                         Sum Sq  Df F value  Pr(>F)
fungroup                   1.87   2  0.6069 0.54656
numsp.fun                 11.14   2  3.6214 0.02942
block                    486.47   4 79.0379 < 2e-16
fungroup:numsp.fun         6.32   4  1.0275 0.39553
fungroup:block            11.43   8  0.9283 0.49542
numsp.fun:block           11.29   8  0.9169 0.50473
fungroup:numsp.fun:block  26.89  16  1.0920 0.36882
Residuals                204.65 133                

> options('digits')
$digits
[1] 7

> options('contrasts')
$contrasts
[1] "contr.sum"  "contr.poly"

> sessionInfo()
R version 2.5.1 (2007-06-27) 
i486-pc-linux-gnu 

locale:

LC_CTYPE=en_CA.UTF-8;LC_NUMERIC=C;LC_TIME=en_CA.UTF-8;LC_COLLATE=en_CA.UTF-8;
LC_MONETARY=en_CA.UTF-8;LC_MESSAGES=en_CA.UTF-8;LC_PAPER=en_CA.UTF-8;LC_NAME=C;
LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_CA.UTF-8;LC_IDENTIFICATION=C

attached base packages:
[1] "stats"     "graphics"  "grDevices" "utils"     "datasets"  "methods"  
[7] "base"     

other attached packages:
    car 
"1.2-7"



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