[R] Help Need with aov()

[Bill Venables]

You don't give us much to go on!

At 11:56 PM 4/30/00 +1200, Ko-Kang Wang wrote:
>Hi there,
>
>I'm using R1.0.1 Windows 98.
>
>This file contains some inputs and an aov function code.  Can someone
>check it for me?  Somehow I got completely different answer when typing
>them in R and in Splus.
>
>Splus gives me this:
>> summary( Turnip.aov )
>Error: Blocks
>          Df Sum of Sq  Mean Sq F Value Pr(F)
>Residuals  3  163.7367 54.57891
>
>Error: Plots %in% Blocks
>                                                       Df   Sum of Sq
>Mean Sq    F Value       Pr(F)
>Variety                                              1     83.9514
>83.9514     8.75282    0.0049136
>Sowing.Date                                      1    233.7077
>233.7077   24.36650    0.0000114
>Sowing.density                                   3    470.3780
>156.7927   16.34730    0.0000003
>Variety:Sowing.Date                          1     36.4514
>36.4514     3.80045    0.0574875
>Variety:Sowing.density                       3      8.6467
>2.8822      0.30050    0.8248459
>Sowing.Date:Sowing.density               3    154.7930     51.5977
>5.37960    0.0029884
>Variety:Sowing.Date:Sowing.density   3      17.9992     5.9997
>0.62554    0.6022439
>Residuals                                          45   431.6108
>9.5914
>
>
>and R gives:
>Error: Blocks
>          Df Sum Sq Mean Sq F value Pr(>F)
>Residuals  1 107.76  107.76
>
>Error: Blocks:Plots
>        Df Sum Sq Mean Sq
>Variety  1  31.02   31.02
>
>Error: Within
>                                                       Df    Sum Sq
>Mean Sq    F value    Pr(>F)
>Variety                                             1       72.34
>72.34        6.3775   0.014525 *
>Sowing.Date                                     1      255.84
>255.84      22.5546  1.547e-05 ***
>Sowing.density                                  1      377.13
>377.13      33.2480  4.033e-07 ***
>Variety:Sowing.Date                         1       31.04
>31.04       2.7366   0.103872
>Variety:Sowing.density                      1        0.20
>0.20         0.0173   0.895712
>Sowing.Date:Sowing.density              1      108.01    108.01
>9.5225   0.003199 **
>Variety:Sowing.Date:Sowing.density  1        5.40        5.40
>0.4763   0.493046
>Residuals                                         54 612.52   11.34
>---
>Signif. codes:  0  `***'  0.001  `**'  0.01  `*'  0.05  `.'  0.1  ` '  1
>
>
>
>Can anyone tell me why this is happening?  Much appreciated...

But there is a pretty large clue in the degrees of freedom column.  It
looks very much as if in R you have not set up Sowing.density as a factor
(with 4 levels) but left it as a quantitative variable.  If that's not the
problem there's not much more I can say from the information you give -
(other than it is most likely your mistake and not that of the software...).

>
>--
>---------------------------------------------------------------------------
--------
>
> Ko-Kang Wang
> Undergraduate Student
> Computer Science/Statistics Double Major
> University of Auckland
> Auckland 1005
> New Zealand
>---------------------------------------------------------------------------
--------
>
>
>
>Attachment Converted: "D:\data\tad\Eudora\attach\Turnip.R"
>
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