Npmc for doing post-hoc after Kruskal

[Farrel Buchinsky]

I followed the threads that enquired about doing post-hoc tests after doing
Kruskal testing. It took me to npmc. But npmc is giving an output I do not
understand. 
I noticed a thread entitled "npmc function: 'x' must be atomic" but there
never appeared to be a resolution.

> npmc(npmcinput)
Error in sort(unique.default(x), na.last = TRUE) : 
        'x' must be atomic

Here is the dataframe I created and called npmcinput
To prove that I have the data set up correctly I ran
> kruskal.test(OtoMax~grp)

        Kruskal-Wallis rank sum test

data:  OtoMax by grp 
Kruskal-Wallis chi-squared = 59.4028, df = 3, p-value = 7.885e-13

   grp OtoMax
1    1      0
2    1      1
3    1      0
4    1      1
5    1      1
6    1      1
7    1      1
8    1      1
9    1      1
10   1      2
11   1      1
12   1      1
13   1      1
14   1      1
15   1      2
16   1      1
17   1      1
18   1      1
19   1      2
20   1      2
21   1      0
22   1      1
23   1      1
24   1      2
25   1      1
26   1      1
27   1      1
28   1      2
29   3      4
30   3      4
31   3      2
32   3      2
33   3      2
34   3      3
35   3      2
36   3      2
37   3      2
38   3      3
39   3      2
40   3      2
41   3      4
42   3      3
43   3      2
44   3      4
45   3      3
46   3      4
47   3      2
48   3      2
49   3      2
50   3      3
51   3      2
52   3      3
53   3      0
54   3      4
55   3      2
56   3      2
57   2      2
58   2      2
59   2      2
60   2      2
61   2      2
62   2      2
63   2      3
64   2      2
65   2      2
66   2      3
67   2      2
68   2      2
69   2      2
70   2      2
71   2      2
72   2      2
73   2      3
74   2      2
75   2      3
76   2      3
77   2      3
78   2      2
79   2      3
80   2      4
81   2      2
82   2      2
83   2      2
84   2      2
85   0      1
86   0      1
87   0      0
88   0      1
89   0      0
90   0      0
91   0      0
92   0      0
93   0      1
94   0      0

Subsequently I renamed grp to be "class" and OtoMax to be "var" and
everything seemed to work.
Is that really the way one has to do it? As a general pointer to my overall
R capabilities- does the documentation say that one has to name them class
and var? Has my e-mail transgressed R etiquette? 

Farrel Buchinsky, MD --- Mobile (412) 779-1073
Pediatric Otolaryngologist
Allegheny General Hospital
Pittsburgh, PA 



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