Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
st: AW: Sign of Lambda in heckman
From
"Martin Weiss" <[email protected]>
To
<[email protected]>
Subject
st: AW: Sign of Lambda in heckman
Date
Mon, 1 Mar 2010 14:53:27 +0100
<>
As [R], p. 651 says: lambda is the product of rho and sigma. If all you are
interested in is the sign, then sigma is irrelevant, since it will always be
positive, being a standard deviation. So you are really asking for
information about rho: I would check the references at the beginning of the
"Methods and formulas" for more insights about its meaning.
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Sascha Steffen
Gesendet: Montag, 1. März 2010 14:27
An: [email protected]
Betreff: st: Sign of Lambda in heckman
Dear All,
I was wondering about an economic interpretation of the sign of the lambda
in a heckman selection model. For example, I am interested in factors
reducing default rates of firms. I only observe the performance of the loan
once the loan is approved. I use a selection model to account for this. My
lambda from the heckman model turns out to be significant and negative. What
is the interpretation? In what direction is the bias? Can I interpret the
negative sign, that information has been used to screen and filter out bad
applicants? What do you think?
Best wishes,
Sascha
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/