[R] model.tables error from aov
John Vokey
vokey at uleth.ca
Thu Dec 18 00:20:47 CET 2008
In addition, your model statement is odd. Note that within-S factor
Type is tested with both the type I and the type II residuals, whereas
only the latter should be used. Try this model instead:
aov.errs.ae <- aov(TrainErrs ~ idio*Type + Error(Subject/
Type),data=learnDat.ae)
or, for more clarity:
aov.errs.ae <- aov(TrainErrs ~ idio*Type + Error(Subject
+Subject:Type),data=learnDat.ae), which explicitly denotes the two
error strata.
On 17-Dec-08, at 4:00 AM, r-help-request at r-project.org wrote:
> Your design seems to be unbalanced: multistatum aov is intended for
> balanced designs. My guess is that one idio subject has two Type=1
> observations: in which case try removing one of them.
>
> On Tue, 16 Dec 2008, Harlan Harris wrote:
>
>> Hi, I'm a new R user, coming from SPSS, and without a particularly
>> strong
>> stats background.
>>
>> I've got a data set that I'd like to do a mixed-design ANOVA with. No
>> missing values. Here's the summary:
>>
>> summary(learnDat.ae)
>> Type Subject idio struct TrainErrs
>> cond
>> 0:20 11 : 3 idio :28 ae :58 Min. : 0.00
>> idioae :28
>> 2:19 12 : 3 nonidio:30 fact: 0 1st Qu.: 6.25
>> idiofact : 0
>> 3:19 14 : 3 Median :11.50
>> nonidioae:30
>> 15 : 3 Mean :13.40
>> 18 : 3 3rd Qu.:16.00
>> 2 : 3 Max. :59.00
>> (Other):40
>>
>> Note that the TrainErrs column is the only numeric column, and I
>> forced
>> everything else to be a factor. (Is that correct?)
>>
>> I then do the following:
>>
>> aov.errs.ae <- aov(TrainErrs ~ (idio*Type) + Error(Subject/Type) +
>> (idio),
>> learnDat.ae)
>>
>> So, idio is between-subjects and Type is within-subjects. This is
>> based on
>> examples I've found elsewhere.
>>
>> summary(aov.errs.ae)
>>
>> This seems to work fine:
>>
>> Error: Subject
>> Df Sum Sq Mean Sq F value Pr(>F)
>> idio 1 179 179 0.89 0.36
>> Type 1 210 210 1.05 0.32
>> Residuals 17 3401 200
>>
>> Error: Subject:Type
>> Df Sum Sq Mean Sq F value Pr(>F)
>> Type 2 515 258 2.44 0.103
>> idio:Type 2 680 340 3.22 0.053 .
>> Residuals 34 3595 106
>> ---
>> Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
>>
>
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-Dr. John R. Vokey
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