[R] {car} outlierTest looses p/q values

[John Fox]

Dear Phil,

After reading your posting several times, I still don't understand what you did. As usual, having a reproducible example illustrating the error would be a great help. I do have a guess about the source of the error: glm() failed in some way for the problematic case.

Best,
 John

------------------------------------------------
John Fox, Professor
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox/
	

On Fri, 17 Oct 2014 12:53:30 +0200
 Phil <chobophil at gmail.com> wrote:
> Hi guys,
> 
> I came across a strange phenomena and can't figure out why it happens by myself so here we go.
> 
> I got a dataframe which consists of double numbers which I want to check, row-wise if there are outliers in the rows.
> 
> So I iterate over the rows and create a glm using the numbers of that particular row. Which might look like this:
> 
> case1)
>          x1        x2        x3        x4        x5        x6 x7        
> x8        x9        x10        x11
>      0.00     3.91     0.00     0.00     0.00   68.03   40.39 0.00     
> 0.00      0.00       4.11
> 
> or like this:
> case2)
>          x1        x2        x3        x4        x5        x6 x7        
> x8        x9        x10        x11
>       1.00     1.00    1.00     1.00     1.00     1.00     1.00 1.00     
> 1.00     1.00      5.34
> 
> or any other combination of double numbers...
> 
> however, using a glm like this:
> 
> glModel <- glm(vector ~ some_other_meta_data_which_is_double_numbers)
> 
> and testing it with:
> 
>   test.Res <- outlierTest(glModel,digits=4,cutoff=Inf,n.max=Inf)
> 
> I always get a result consisting of the desired p and q values but not if the vector I use looks like case2. There is no error message and the computation does not stop either.
> However, all p and q values are produced except for the last value x11.
> 
> Any idea why this particular value gets dropped from the output of the outlierTest Method in the car package.
> 
> Here is the sessioninfo:
> 
>   sessionInfo()
> R version 3.1.1 (2014-07-10)
> Platform: x86_64-redhat-linux-gnu (64-bit)
> 
> locale:
>   [1] LC_CTYPE=en_US.utf8       LC_NUMERIC=C
>   [3] LC_TIME=en_US.utf8        LC_COLLATE=en_US.utf8
>   [5] LC_MONETARY=en_US.utf8    LC_MESSAGES=en_US.utf8
>   [7] LC_PAPER=en_US.utf8       LC_NAME=C
>   [9] LC_ADDRESS=C              LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.utf8 LC_IDENTIFICATION=C
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods base
> 
> other attached packages:
> [1] ggplot2_1.0.0      car_2.0-21         RColorBrewer_1.0-5 iNEXT_1.0
> [5] vegan_2.0-10       lattice_0.20-29    permute_0.8-3
> 
> loaded via a namespace (and not attached):
>   [1] colorspace_1.2-4 compiler_3.1.1   digest_0.6.4 grid_3.1.1
>   [5] gtable_0.1.2     labeling_0.3     MASS_7.3-33 munsell_0.4.2
>   [9] nnet_7.3-8       plyr_1.8.1       proto_0.3-10 Rcpp_0.11.2
> [13] reshape2_1.4     scales_0.2.4     stringr_0.6.2    tools_3.1.1
> 
> Any help is highly appreciated.
> 
> Thanks
> 
> Phil
> 
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