[Limdep Nlogit List] Question on MVPROBIT Command

[Jason Bergtold]

Bill, 

I do want -inf < mu1 < mu2 < mu3 <mu4 < mu 5 < +inf, such that mu1 = -mu5 and m2 = -mu4. I apologize for not putting in the appropriate negative signs. 

Jason 

-----Original Message-----
From: Limdep <limdep-bounces at mailman.sydney.edu.au> On Behalf Of William Greene via Limdep
Sent: Friday, May 7, 2021 6:27 PM
To: Limdep and Nlogit Mailing List <limdep at mailman.sydney.edu.au>
Cc: William Greene <wgreene at stern.nyu.edu>
Subject: Re: [Limdep Nlogit List] Question on MVPROBIT Command

This email originated from outside of K-State.


Jason.  mu5 = 1 and mu2 = mu4 do not accomplish what you are trying to do.
These
constraints will force certain probabilities to equal zero or be negative.
I can't tell what
you are restricting, but in order for the model to be kosher, you must have -inf < 0 <  mu1 < mu2 < mu3 <mu4 < mu 5 < +inf. If mu5 = 1 but mu4 > 1, then your model produces zero probabilities.  Likewise, forcing mu2 = mu4 will make a mess of things. You can't have mu2 = mu4 and have mu3 < mu4 and mu3 > mu2.
Regards,
Bill Greene


On Fri, May 7, 2021 at 6:32 PM Jason Bergtold <bergtold at ksu.edu> wrote:

> Dear Group:
>
> I am trying to run a Random Valuations Model following Wang and in 
> Alberni et al (2003) (Analysis of contingent valuation data with 
> multiple bids and response options allowing respondents to express 
> uncertainty." I have a ordered response variable with 7 ordered 
> categories from definitely no to definitely yes. I am modeling this 
> using an ordered Probit model. The base model would estimate 7 
> threshold values with the first and last being set to -inf and inf, 
> respectively. The middle 5 threshold values for the model, call them 
> mu1 < mu2 < mu 3 <mu4 < mu 5. I want to set two restrictions on the 
> model that mu 1 - mu5 = 0 and mu2 - mu 4 = 0, to make the estimation 
> of the threshold parameters "symmetric". I am wondering how to impose this restriction using the Ordered command.
>
> Regards,
>
> Jason
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William Greene
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