[R] problem finding p-value for entropy in reldist package

VictorDelgado victor.maia at fjp.mg.gov.br
Mon Jul 11 19:24:55 CEST 2011


Hi Amy Wesolowski,

I don't have a straightfoward answer to you question. I have been working
with reldist too, and the 'rpy' and 'rpluy' functions described by "Applying
Relative Distribution Methods in R" are also not working here in my 2.9.1
R-version. I think its because they are reldist internall function, so,
maybe its possible that they only work with previous objects and set ups...

But if you look to internal parametres of reldist, you could set "ci =
TRUE", it's constructs the confidence interval for entropy by the proportion
of original cohort. It's still unhelpfull to understand how this intervall
is constructed, and also does not show the overall interval, but you can se
the values with $ci.

By the Handcock and Morris (1998) paper is posible to intuit that they are
comparing the 0.00 entropy with the 95% Confidence Interval around the
estimate. For example, in this artigle, pag. 74, they reach an overall
entropy of 0.125, the lower 95%_CI is 0.092. The 0.00 comparision is far
below this lower bound, so its resonable to think the p-value is realy
0.000.

But it's only a clue to approximate the true p-value. But we still needing
to see: 1) how this intervall is constructed (I have no idea what
distribution the entropy should have, and if it changes by data) and 2)
Knowing the first point, how to set alpha values). 

Good luck,

Victor Delgado
cedeplar.ufmg.br P.H.D. student
www.fjp.mg.gov.br reseacher

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