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| From | rachel grant <rachelannegrant@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: Regression Equation in ZINB regression |
| Date | Tue, 20 Sep 2011 17:00:38 +0100 |
Thanks Partho for taking the time to help me. It is becoming clearer. I am going to look into it further and I'll come back to the list if I need more help thanks again Rachel On 20 September 2011 12:50, Partho Sarkar <partho.ss+lists@gmail.com> wrote: > 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/ > -- 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/