[R] Warning message for TukeyHSD test - error

[Valentina Lauria]

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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