[R] repeated measures ANOVA - among group differences

Mike Lawrence Mike.Lawrence at dal.ca
Wed Apr 1 13:21:05 CEST 2009


If Month is nested within Quadrat I think you want:
aov(ProportioninTreatment ~ Treatment*Month +Error(Quadrat/Month), RM)

If Treatment is also nested within Quadrat, you want:
aov(ProportioninTreatment ~ Treatment*Month
+Error(Quadrat/(Treatment*Month)), RM)


On Wed, Apr 1, 2009 at 12:42 AM, Jessica L Hite/hitejl/O/VCU
<hitejl at vcu.edu> wrote:
>
>
> I have data on the proportion of clutches experiencing different fates
> (e.g., 4 different sources of mortality) for 5 months . I need to test 1)
> if the overall proportion of these different fates is different over the
> entire study and 2) to see if there are monthly differences within (and
> among) fate types. Thus, I am pretty sure this is an RM analysis -( I
> measure the same quadrats each month).
>
> I am fine running the analysis in R - with the code below, however, there
> is no output for the among group variation...this is an important component
> - any ideas on how to solve this problem?
>
> I have included code and sample data below.
>
> Many thanks in advance for help and suggestions.
>
> J
>
>  both.aov <- aov(ProportioninTreatment ~ factor(Treatment)*factor(Month) +
> Error(factor(Quadrat)), RM)
>
> Error: factor(id)
>          Df  Sum Sq Mean Sq F value Pr(>F)
> Residuals  3 0.51619 0.17206               #####why only partial output
> here? #######
>
> Error: Within
>                   Df Sum Sq Mean Sq F value   Pr(>F)
> factor(Fate1)       3 1.2453  0.4151  3.5899 0.017907 *
> time                1 0.9324  0.9324  8.0637 0.005929 **
> factor(Fate1):time  3 0.9978  0.3326  2.8763 0.042272 *
> Residuals          69 7.9783  0.1156
>
>
>
>
> Fate1 Proportion in Fate      ASIN  Month Quadrat
> 1     0.117647059 0.350105778 1     1
> 1     0     0     2     1
> 1     0.111111111 0.339836909 3     1
> 1     0     0     4     1
> 1     0     0     5     1
> 1     0     0     1     2
> 1     0     0     2     2
> 1     0.2   0.463647609 3     2
> 1     0.25  0.523598776 4     2
> 1     0.111111111 0.339836909 5     2
> 1     0     0     1     3
> 1     0     0     2     3
> 1     0     0     3     3
> 1     0.384615385 0.668964075 4     3
> 1     0     0     5     3
> 1     0     0     1     4
> 1     0     0     2     4
> 1     0     0     3     4
> 1     0.166666667 0.420534336 4     4
> 1     0     0     5     4
> 2     0.352941176 0.636132062 1     1
> 2     0.2   0.463647609 2     1
> 2     0.333333333 0.615479708 3     1
> 2     1     1.570796327 4     1
> 2     0     0     5     1
> 2     0.5   0.785398163 1     2
> 2     0     0     2     2
> 2     0.6   0.886077124 3     2
> 2     0.416666667 0.701674124 4     2
> 2     0.222222222 0.490882678 5     2
> 2     0     0     1     3
> 2     0.2   0.463647609 2     3
> 2     0     0     3     3
> 2     0.461538462 0.746898594 4     3
> 2     0     0     5     3
> 2     0     0     1     4
> 2     0     0     2     4
> 2     0.307692308 0.588002604 3     4
> 2     0.666666667 0.955316618 4     4
> 2     0     0     5     4
> 3     0     0     1     1
> 3     0     0     2     1
> 3     0.444444444 0.729727656 3     1
> 3     0     0     4     1
> 3     1     1.570796327 5     1
> 3     0.5   0.785398163 1     2
> 3     0     0     2     2
> 3     0     0     3     2
> 3     0.25  0.523598776 4     2
> 3     0.555555556 0.841068671 5     2
> 3     0     0     1     3
> 3     0     0     2     3
> 3     0     0     3     3
> 3     0.153846154 0.403057075 4     3
> 3     0.666666667 0.955316618 5     3
> 3     0     0     1     4
> 3     0     0     2     4
> 3     0     0     3     4
> 3     0     0     4     4
> 3     0.875 1.209429203 5     4
> 4     0.294117647 0.573203309 1     1
> 4     0.2   0.463647609 2     1
> 4     0     0     3     1
> 4     0     0     4     1
> 4     0     0     5     1
> 4     0     0     1     2
> 4     0     0     2     2
> 4     0     0     3     2
> 4     0.083333333 0.292842771 4     2
> 4     0.111111111 0.339836909 5     2
> 4     0     0     1     3
> 4     0     0     2     3
> 4     0     0     3     3
> 4     0     0     4     3
> 4     0.166666667 0.420534336 5     3
> 4     0     0     1     4
> 4     0     0     2     4
> 4     0.461538462 0.746898594 3     4
> 4     0     0     4     4
> 4     0.125 0.361367124 5     4
>        [[alternative HTML version deleted]]
>
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-- 
Mike Lawrence
Graduate Student
Department of Psychology
Dalhousie University

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