[Limdep Nlogit List] Question about bivariate probit
wgreene at stern.nyu.edu
Fri Jul 21 06:35:59 AEST 2017
Jane. (1) RHO is not the correlation of z1 and z2. It is the correlation
of the disturbances.
Your manual tells you how to compute a tetrachoric correlation. You should
(2) Your WALD command is incorrect. The function you want to analyze is
RHO over the
square root of the variance. Your use of the ^ in the function asks the
program to raise rho
to the power 1/var(rho). You should just trust the probit output, It is
giving you the right test
statistic, although, you are not interpreting RHO correctly.
On Thu, Jul 20, 2017 at 10:51 AM, Jane Kolodinsky <Jane.Kolodinsky at uvm.edu>
> I am trying to determine whether an individual's opposition to genetic
> engineering is jointly determined with seeing a label that says "produced
> using GE."
> I ran the wald test to "automate" the test and they are contradictory.
> RHO(1,2)| -.01910 .06371 -.30 .7644 -.14396 .10577
> Above is the relevant output from the bivariate probit: bivariateprobit;
> Lhs=z1, z2; Rh1=x1; rh2= x2$
> The prob value is .76---do not reject rho>0.
> I also calculated the wald test following p. E21-9 in the Limdep manual.
> calc;list; waldtest=rho^/varrho; pvalue=1-chi(waldtest,1)$
> That output is:
> CALC] WALDTEST= 246.3811130
> [CALC] PVALUE = .0000000
> Calculator: Computed 2 scalar results
> The output is telling me not to reject they null hypothesis that rho =0
> and the Wald test is telling me to reject the null hypothesis.
> Please advise.
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