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st: gausshermite question


From   "David Rivenbark" <[email protected]>
To   <[email protected]>
Subject   st: gausshermite question
Date   Sat, 29 Mar 2014 14:44:53 -0400

	I'm using -gausshermite- to approximate the expected value of a
variable 0 <= z <= 1 that is distributed logit-normal with mean 0.4528 and
variance 0.16. I have altered the original ADO file to allow me to set more
than 100 observations, thus more than 98 nodes. 

	With 150 nodes -myghermite- retuned approximately 0.60 as it should
(Frederic and Lad 2008).

. myghermite 1/(1+exp(-x)) , sigma(.4) mu(.4528) d n(150) observations(152)
int_R (1/(1+exp(-x)))g(x/sigma=.4)dx=  0.60735817

However, when I set 200 nodes -myhermite- returns 0. 

. myghermite 1/(1+exp(-x)) , sigma(.4) mu(.4528) d n(200) observations(202)
int_R (1/(1+exp(-x)))g(x/sigma=.4)dx=  0.00000000

	What is causing the zero value? Is there a way to fix this issue?

Reference:

Patrizio Frederic & Frank Lad (2008) Two Moments of the Logitnormal
Distribution, Communications in Statistics - Simulation and Computation,
37:7, 1263-1269


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