On Mon, 19 Oct 2009, Dorian Litvine wrote:
My name is Dorian, I'm trying to estimate the data of a double
bounded
dichotomous choice (contingent valuation) thanks to a maximum
likelihood estimation with a linear specification (From E. Flachaire).
But when I put the command, then GRETL gives several errors messages
as "missing values found". I think the model may not be specified for
linear. But it is strange because when I put initial values quite high
(5) then it converges but I don't know if results are "possible". May
someone help me? Here is the code
genr alpha=3
genr sigma=1
logl=(1-CD1)*(1-CD2)*log(Pnn)+(1-CD1)*CD2*log(Pny)+CD1*(1-CD2)*log(Pyn)+CD1*CD2*log(Pyy)
series Pnn=1/(1+exp(-(BID2-alpha)/sigma))
series
Pny=1/(1+exp(-(BID1-alpha)/sigma))-1/(1+exp(-(BID2-alpha)/sigma))+(BID2>BID1)*100
series
Pyn=1/(1+exp(-(BID2-alpha)/sigma))-1/(1+exp(-(BID1-alpha)/sigma))+(BID2<BID1)*100
series Pyy=1-1/(1+exp(-(BID2-alpha)/sigma))
params alpha sigma
And attached you have the results if I set the initial values at 5.
You need to tell us what your model actually is. You give a code
fragment above, and this could be turned into a block requesting
mle estimation by wrapping all but the first two lines in
mle ...
<your code here>
end mle
But the code does not match the results you attached: above we
have only two parameters, alpha and sigma, while you report
estimates of three: alpha0, alpha1 and sigma.
Allin Cottrell