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From |
Stas Kolenikov <skolenik@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Multinomial logit model with selection |

Date |
Fri, 2 Mar 2012 13:08:43 -0500 |

Teresa, cleanup issues in your post: 1. there is no -selmlog- in Stata world, as we know it. -findit selmlog- returns a reference to -svyselmlog- on SSC. If a package is not downloadable, it is nearly as good as non-existent. Without knowing what -selmlog- produces, it is impossible to say how to interpret its output. 2. References to the papers would be helpful. Especially if coupled with links to full text or to RePEc, at least. I can answer your question 2: I don't think any of the interpretation changes. You are doing corrections in a different way, that's all. What you called DMF(1) is more flexible, although not so internally consistent compared to DMF(0), but as far as I can recall Bourguignon's paper, it worked in a greater variety of settings. On Fri, Mar 2, 2012 at 11:45 AM, T.Randazzo <tr81@kent.ac.uk> wrote: > Dear Stata List, > I am trying to analyze how receiving remittances can affect the household expenditure behaviour in Senegal. > I have four types of household (HH_type) > HH_type: > 1. HH who do not receive remittances > 2. HH who receive remittances from national migrants > 3. HH who receive remittances from international migrants > 4. HH who receive remittances both from national and international migrants > > I would like to investigate if differences exist in some specific expenditure (food, durable goods, education, health...) > > The Model that I am trying to apply is a Multinomial logit model with selection as presented by Dubin and McFadden (1984) and revisited by Bourguignon, Fournier and Gurdand (2007). > > The original DMF’s model [DMF(0)] is based on two assumptions: linearity assumption between the error term in the outcome equation and the error term in the choice equation; correlation coefficients between the two error terms sum up to zero. > The DMF’ model [DMF(1)] proposed by Bourguignon et al (2007) relaxes the second assumption > I am using the Selmlog command in Stata10. > > When I consider DMF(0) I end up with 3 Mills’ ratio (M-1). > When I apply DMF(1) I end up with 4 Mills’ ratio > > 1) How can I test if the restriction on the correlation parameters is correct? > 2) Passing from 3 to 4 Mills’ ratios how does the interpretation of that relevant coefficients change? > Model DMF(1): > Gen health1= health > Replace health1=. if HH_type !=1 > selmlog health1 varlist, select (HH_type= varlist_m) dmf(1)bootstrap(100) gen(rh1_1) > > Gen health2= health > Replace health2=. if HH_type !=2 > selmlog health2 varlist, select (HH_type= varlist_m) dmf(1)bootstrap(100) gen(rh1_1) > > Considering expenditure on health, I have found that for HH_type=1 rh1_1, rh1_2 and rh1_4 are insignificant while rh1_3 is significant. For HH_type=2 only rh2_2 is significant. > 3) How should I interpret those results? > I tried to compare the results obtained from the command selmlog with the following prestige: > a) run a mlogit where the dependent variable is HH_type > b) calculate the mills ratios > > predict p1, outcome(1) > predict p2, outcome(2) > predict p3, outcome(3) > predict p4, outcome(4) > > gen trnsp1=(p1*ln(p1))/(1-p1) > gen trnsp2=(p2*ln(p2))/(1-p2) > gen trnsp3=(p3*ln(p3))/(1-p3) > gen trnsp4=(p4*ln(p3))/(1-p4) > > gen mills1= 4* ln(p1)+ trnsp2 + trnsp3 + trnsp4 > > gen mills2= 4* ln(p2)+ trnsp1 + trnsp3 + trnsp4 > > gen mills3= 4* ln(p3)+ trnsp1 + trnsp2 + trnsp4 > > gen mills4= 4* ln(p4)+ trnsp1 + trnsp2 + trnsp3 > > c) Add the Mills’ ratios to the second step equation (we are considering expenditure on health) > reg health1 varlist mills1 mills2 mills3 mills4 > reg health2 varlist mills1 mills2 mills3 mills4 > reg health3 varlist mills1 mills2 mills3 mills4 > reg health4 varlist mills1 mills2 mills3 mills4 > > 4) Does this prestige correspond to the one performed using the selmlog command? If it is, why don’t I get the same outcomes? > > Your help to understand the model better would be very appreciate, > > Sincerely, > > Teresa Randazzo > PhD candidate, University of Kent > * > * 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/ -- Stas Kolenikov, also found at http://stas.kolenikov.name Small print: I use this email account for mailing lists only. * * 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/

**Follow-Ups**:**RE: st: Multinomial logit model with selection***From:*"T.Randazzo" <tr81@kent.ac.uk>

**References**:**st: Multinomial logit model with selection***From:*"T.Randazzo" <tr81@kent.ac.uk>

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