On Nov 25, 2012, at 2:06 PM, sm2284 wrote:
Thank you David I think that makes sense.
As a side note I have been doing some work with fish abundance in
aquaria. The TRUE column is the actual amount of fish in the tank,
so a questionable practice but a valid one??
It complicates the human interpretation of code to have reserved words
(of which 'TRUE' is one) used as a name of an object (or an object
element. You seen to be getting away with it because you are not
reporting an error message, but it is deemed poor practice. If you
have the fortunes package installed try typing:
fortunes::fortune("dog")
Usually it does cause the interpreter confusion if you only use
function names as column names, but I can create pathological results
if I test for TRUE > 500 in a dataset where half of the rows should
meet that criterion. Since TRUE becomes 1 when coerced to numeric, I
get no rows from subset().
--
David.
Thanks again,
Stephen
On 25 Nov 2012, at 20:41, David Winsemius [via R] wrote:
On Nov 25, 2012, at 4:55 AM, sm2284 wrote:
Dear R-ers,
I am currently running some Wilcoxon tests in R-64.
How do I find the degrees of freedom in the output I am receiving?
wilcox.test(good$TRUE, good$x4a, paired=FALSE)
Wilcoxon rank sum test with continuity correction
data: good$TRUE and good$x4a
W = 2455, p-value < 2.2e-16
alternative hypothesis: true location shift is not equal to 0
When using wilcox.test with two samples, the function passes some
version of the Rank-Sum statistic W to the pwilcox function followed
by the lengths of the two vectors. So I suppose you could say the
sample sizes are the "degrees of freedom". Reasoning informally I
would think the smaller of those lengths would be the most important
in determining stability of the inference.
BTW, methinks it a very questionable practice to name a column
'TRUE'.
--
David Winsemius, MD
Alameda, CA, USA
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