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From |
Partho Sarkar <partho.ss+lists@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Regression Equation in ZINB regression |

Date |
Tue, 20 Sep 2011 17:20:09 +0530 |

Oops, sorry again! My apologies- I am doing this in between other work. I meant to write: E[yi|xi]=count for x=xi =lambda[i]=a0+a1xi + etc, i.e., the probability lambda is different for different levels of xi. and L(y1,y2,..,yn)=F(lambda[1],lambda[2],...,lambda[n])=G(x1,x2,...,xn) Partho On Tue, Sep 20, 2011 at 5:09 PM, Partho Sarkar <partho.ss+lists@gmail.com> wrote: > Rachel, it seems you posted the same question under 2 headers- I just > replied on the thread: Regression Equation for Zero inflated negative > binomial. I wanted to make a slight correction- I said the parameter > lambda is is the LHS in the regression, which is not quite correct. > The mean (or expected) count is equal to lambda. So we really use the > fact that : > > E[yi|xi]=count for x=xi =lambda=a0+a1xi + etc. > > to get the "likelihood" of observing all the yi's as a function of the > observed xi's: > > L(y1,y2,..,yn)=F(lambda)=G(x1,x2,...,xn) > > and then maximize this likelihood function to estimate lambda. > > Hope this helps > > Partho > > On Tue, Sep 20, 2011 at 4:19 PM, Partho Sarkar > <partho.ss+lists@gmail.com> wrote: >> My post crossed yours in the mail! Hope you can manage now. >> >> Partho >> >> On Tue, Sep 20, 2011 at 4:03 PM, rachel grant <rachelannegrant@gmail.com> wrote: >>> Thank you Partho. Thank you all for your patience. >>> I have now understood that I cannot get Stata to do this and I need to >>> reconstruct by inserting my co-efficients into the equation. Fine >>> >>> Now the problem I have is finding a general equation for ZINB in order >>> to reconstruct. >>> Is the general equation for ZINB the same as Poisson? I cannot find >>> anywhere a general equation for ZINB. >>> I could use a general log-linear Poisson type equation but would this >>> be correct? and how do I deal with the inflated part, is this merely a >>> seperate log-linear eqn, or is it incorporated into th general ZINB >>> eqn. Thanks, Rachel >>> >>> On 19 September 2011 08:13, Partho Sarkar <partho.ss+lists@gmail.com> wrote: >>>> Hi Rachel >>>> >>>> Just to clarify: in order to actually get the "regression equation", >>>> by which I assume you mean something like >>>> >>>> yhat=12.56+2.6*x1+0.34*x2 , >>>> >>>> you do need to reconstruct the equation form the output displayed (as >>>> exemplified by Anees's results). You could see this page for an >>>> example: http://dss.princeton.edu/online_help/analysis/interpreting_regression.htm >>>> . >>>> >>>> With a little more programming effort, this process could be automated >>>> using e-class macros etc. (There is very probably a user-written >>>> program to do this somewhere out there- -estadd- from here >>>> http://repec.org/bocode/e/estout/ might help partly, and you can >>>> search the rich REPEC archives). >>>> >>>> (In this sense Stata may not be as "user friendly" as Minitab or even >>>> some more ambitious other packages, which helpfully report the exact >>>> "prediction equation" in the form you might want, but then it can do >>>> so much more besides!) >>>> >>>> Hope this helps >>>> >>>> Partho >>>> >>>>> On Mon, Sep 19, 2011 at 12:34 AM, rachel grant <rachelannegrant@gmail.com> wrote: >>>>>> >>>>>> I have searched the help files but I cannot understand how to get >>>>>> Stata to display the regression equation. >>>>>> If anyone is able to help, without referring me to manual, it would be >>>>>> really appreciated. >>>>>> >>>>>> -- >>>>>> regards, Rachel Grant >>>>>> * >>>>>> * 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/ >>>> >>> >>> >>> >>> -- >>> regards, Rachel >>> >>> * >>> * 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: Regression Equation in ZINB regression***From:*rachel grant <rachelannegrant@gmail.com>

**References**:**Re: st: Regression Equation in ZINB regression***From:*rachel grant <rachelannegrant@gmail.com>

**Re: st: Regression Equation in ZINB regression***From:*Partho Sarkar <partho.ss+lists@gmail.com>

**Re: st: Regression Equation in ZINB regression***From:*rachel grant <rachelannegrant@gmail.com>

**Re: st: Regression Equation in ZINB regression***From:*Partho Sarkar <partho.ss+lists@gmail.com>

**Re: st: Regression Equation in ZINB regression***From:*Partho Sarkar <partho.ss+lists@gmail.com>

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