[R] Warning message for TukeyHSD test - error

[Rmh]

you have only 1 df for tryptophan.
make it a factor and then all shoukd work.

Sent from my iPhone

> On Mar 21, 2014, at 12:38, Valentina Lauria <valentina.lauria at plymouth.ac.uk> wrote:
> 
> 
> Dear R list,
> 
> I am trying to fit a one way anova with just one factor and 3 levels. One of my levels is significant
> 
>> av2<-aov(site~Tryptophan, data=datafit)
>> summary(av2)
>            Df Sum Sq Mean Sq F value Pr(>F)
> Tryptophan   1  155.3  155.32   5.875  0.025 *
> Residuals   20  528.8   26.44
> ---
> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> 
> But when I try to compute the Tukey test I get this strage warning message and no values but only NANs
> 
> 
>> summary(aov(Tryptophan~as.factor(site), data=datafit))
>                Df Sum Sq Mean Sq
> as.factor(site) 21  31394    1495
> 
>> test<-TukeyHSD(aov(Tryptophan~factor(site), data=datafit))
> Warning message:
> In qtukey(conf.level, length(means), x$df.residual) : NaNs produced
> 
>> test
>  Tukey multiple comparisons of means
>    95% family-wise confidence level
> 
> Fit: aov(formula = Tryptophan ~ factor(site), data = datafit)
> 
> $`factor(site)`
>             diff lwr upr p adj
> 2-1       -103.70 NaN NaN   NaN
> 3-1       -119.85 NaN NaN   NaN
> 4-1         20.40 NaN NaN   NaN
> 5-1        -70.24 NaN NaN   NaN
> 6-1          7.16 NaN NaN   NaN
> 7-1         22.57 NaN NaN   NaN
> 8.1-1       11.10 NaN NaN   NaN
> 8.2-1      -13.38 NaN NaN   NaN
> 9-1         -5.55 NaN NaN   NaN
> 10-1        -8.88 NaN NaN   NaN
> 11-1        -4.21 NaN NaN   NaN
> 12-1        19.92 NaN NaN   NaN
> 13-1        10.89 NaN NaN   NaN
> 14.1-1       8.85 NaN NaN   NaN
> 14.2-1      -0.15 NaN NaN   NaN
> 15-1        21.76 NaN NaN   NaN
> 16-1        12.45 NaN NaN   NaN
> 
> etc etc...
> 
> Could anyone help me or point me to the right direction?
> 
> Thank you very much in advance.
> 
> Kind Regards,
> Valentina
> 
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