[RkWard-devel] wilcoxon & ansari_bradley tests

[Thomas Friedrichsmeier]

On Friday 02 February 2007 01:51, SJR wrote:
> wilcoxon & ansari_bradley tests are ready. From my point of view they are
> complete but need intensive testing.

Great!

Some things I noted:

- As fars as I can see, the variable "rk.temp.print.conf.level" is no longer 
actually needed. So it should be removed.

- "rk.temp.length.x" (in the two "inexact" tests) is only needed in one place. 
Therefore I suggest to save the variable, and adjust the test to
if (length (eval (rk.temp.x)) < 50) instead of if (rk.temp.length.x < 50). 
Overall that should be slightly easier to read.

- I'd further suggest to move that note out of the rk.header (), and instead 
place it at the very end (after rk.results()) as:
if (length (eval (rk.temp.x)) < 50) rk.print ("Note: There are less than...")
After all, that's not a parameter, but an info.

- Does this note recommed turning on the "compute exact p-value" option, or 
does it recommed to use the exact version of the test? I don't have any 
background knowledge on the difference between these two.

- I'm not quite happy with all that if and paste for the H1. It's too much 
noise for a simple description. Maybe we will need a helper function 
rk.describe.alternative() for that in the rkward library. For now, it's ok. 
Definitely something to keep in mind for after 0.4.6, though.

- However, this is wrong for the Ansari-Bradley tests! I was not familiar with 
this test before, but it does not test for difference in sample means, but 
for a difference in variance. So writing "x is greater than y" is not 
correct. For an easy way out, just write "greater", "less" or "two.sided" for 
now.

Regards
Thomas
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