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From |
Austin Nichols <austinnichols@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: Which test to use? |

Date |
Thu, 19 May 2011 17:56:55 -0400 |

Al-- Or just test whether constants and coefs differ, but it would be easier to decide among statistical models if there were a theoretical model in evidence, even a verbal one. A simulation seems in order, but what dgp to simulate? Who knows? clear input decision X Y 34 1 0 34 1 0 56 0 0 77 0 1 23 0 0 50 0 1 70 0 0 80 0 1 90 0 1 end biprobit X Y decision test [X]_cons=[Y]_cons test [X]decision=[Y]decision, accum g T=X+2*Y mlogit T dec test [0]_cons=[1]_cons test [0]decision=[1]decision, accum test [0]decision, accum test [0]_cons, accum On Thu, May 19, 2011 at 3:30 PM, Feiveson, Alan H. (JSC-SK311) <alan.h.feiveson@nasa.gov> wrote: > Here's a shot at answering Toby's question: > > One can express the marginal frequencies of X and Y in terms of their joint distribution. Because we are given P(X=1, Y=1) = 0, there are three possible outcomes T: > > T=1: (X=0, Y=0) (with probability p1) > T=2: (X=0, Y=1) (with probability p2) > T=3: (X=1, Y=0) (with probability p3) > > In general T has a trinomial distribution with cell probabilities (p1, p2 and p3 ), however the > values of p1, p2, and p3 might change with covariates. > > So one possible method of addressing Toby's question is to use a multinomial logit (or probit) model. After fitting the model, one can compare P(X = 1) with P(Y = 1); i.e. p3 with p2 for particular values of the covariates (if there are covariates), otherwise directly. > > Al Feiveson > > -----Original Message----- > From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Toby > Sent: Thursday, May 19, 2011 3:12 AM > To: statalist@hsphsun2.harvard.edu > Subject: st: Which test to use? > > Hello, > > I have data of the following character > > > decision X Y > 34 1 0 > 34 1 0 > 56 0 0 > 77 0 1 > 23 0 0 > > > X and Y take the function of categorizing the variable decision. If I > take the mean value of X I get the frequency of decision that could be > classifed as X, the same holds for Y. It could never be that X and Y > take the value 1 at the same time. > Now I want to test whether the frequency of X is significantly > different from the frequency of Y. Can anybody help me figuring out > which statistical test I have to use? > > Kind Regards, > Toby * * 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/

**References**:**st: Which test to use?***From:*Toby <spiegeldesaster@googlemail.com>

**st: RE: Which test to use?***From:*"Feiveson, Alan H. (JSC-SK311)" <alan.h.feiveson@nasa.gov>

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