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From |
Jeph Herrin <junk@spandrel.net> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Difference in Difference for Proportions |

Date |
Fri, 18 Sep 2009 10:00:13 -0400 |

Thanks Austin, Yes, I should have specified the -rd- option, I meant the linear link function. I've become a fan of using binary (and binomial) linear regression for testing hypotheses. cheers, Jeph Austin Nichols wrote:

Jeph-- Doesn't the interaction problem discussed in http://www.stata-journal.com/sjpdf.html?articlenum=st0063 also rear its ugly head here? Probably also have to be careful of SEs--if the total populations are summed weights from a survey, significance will likely be overstated. I'd probably go to -svy:tab- first in that case... sysuse psidextract, clear keep if t>5 set seed 1 g f=ceil(uniform()*1000) egen pop=total(f), by(south t) svyset [pw=f], strata(t) egen gp=group(t south), lab svy:tab gp union if t>5, row ci lincom _b[p42]-_b[p22]-(_b[p32]-_b[p12]) g txsouth=t*south egen y=total(union*f), by(gp) bys gp: replace y=. if _n<_N li y t south pop if y<. binreg y t south txsouth, n(pop) binreg union t south txsouth [pw=f] logit union t south txsouth [pw=f] findit inteff On Thu, Sep 17, 2009 at 4:53 PM, Jeph Herrin <junk@spandrel.net> wrote:Not sure whether this helps you, but I would normally test this with an interaction term in a model. For instance gen txsouth=t*south binreg f t south txsouth, n(pop) Then testing the coefficient on -txsouth- is the same as testing whether there is a significant difference in differences. hth, Jeph Misha Spisok wrote:Hello, Statalist, In brief, how does one test a difference in difference of proportions? My question is re-stated briefly at the end with reference to the variables I present. A formula and/or reference would be appreciated if no command exists.* * 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/

**Follow-Ups**:**Re: st: Difference in Difference for Proportions***From:*Misha Spisok <misha.spisok@gmail.com>

**References**:**st: Difference in Difference for Proportions***From:*Misha Spisok <misha.spisok@gmail.com>

**Re: st: Difference in Difference for Proportions***From:*Jeph Herrin <junk@spandrel.net>

**Re: st: Difference in Difference for Proportions***From:*Austin Nichols <austinnichols@gmail.com>

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