[Rd] Bug in FEXACT: gave negative key (PR#6986)
Peter Dalgaard
p.dalgaard at biostat.ku.dk
Thu Jun 17 12:25:36 CEST 2004
fc at maths.uq.edu.au writes:
> Hello,
>
> I'm using R to apply Fishers exact test to a whole pile of
> contingency tables, and I've run into the bug shown below.
>
> regards,
>
> Francis
>
> --
>
> > dat1 = matrix(c(0,1,0,1,0,0,1,0,0,0,1,0,1,0,0,1,0,0,0,1,0,1,0,0,1,0,0,0,0,
> 1,1,0,0,1,0,0,1,0,0,1,0,0,3,0,0,2,0,0,1,0,0,0,1,0,0,2,0,0,
> 2,0,0,1,0,1,0,0,3,0,0,2,0,0,0,1,0,5,0,0,0,1,0,1,0,0), nrow=3)
>
> > fisher.test( dat1 )
>
> Error in fisher.test(dat1) : Bug in FEXACT: gave negative key
I suppose it counts as a bug when FEXACT says so. However it is most
likely caused by integer overrun, and so really a code for "problem too
large". I.e. we can probably fix the error message, put not get
fisher.test to do the problem. Consider instead
> chisq.test(dat1,sim=T,B=50000)
Pearson's Chi-squared test with simulated p-value (based on 50000
replicates)
data: dat1
X-squared = 80, df = NA, p-value = 2e-05
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--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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