On 06 Feb 2015, at 16:58 , Michael Dewey <i...@aghmed.fsnet.co.uk> wrote:
> Dear Mohamed > > Your dataset did not make it through, the list strips most attachments. > > In my area of application I would be suspicious that such an odds ratio was > the result of a data error or my misunderstanding of the underlying science. > You are probably in the best position to judge both of these in your area. > If both variables are binary, a table would be informative: with(divs, table(Div, PRFD)) The output is roughly consistent with odds 1:30 if PRFD==0 and 3:1 if PRFD==1. That sounds extreme, but not entirely implausible, depending on field of application. > Michael > > > On 06/02/2015 07:42, Mohamed Farah wrote: >> I have run a logit regression with two categorical variables (with 0 and 1) >> as the values. i.e. payment (1) / non-payment(0) on profit (profitable =1, >> non-profitable=0) on 375 entities. Here is the result from R: >> >> >> >>> divgress <-glm(Div~PRFD, family=binomial(link="logit"), data=divs) >>> summary(divgress) >> >> Call: >> glm(formula = Div ~ PRFD, family = binomial(link = "logit"), >> data = divs) >> >> Deviance Residuals: >> Min 1Q Median 3Q Max >> -1.6765 -0.2626 0.7502 0.7502 2.6017 >> >> Coefficients: >> Estimate Std. Error z value Pr(>|z|) >> (Intercept) -3.3499 0.7194 -4.656 3.22e-06 *** >> PRFD 4.4738 0.7311 6.119 9.41e-10 *** >> --- >> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 >> >> (Dispersion parameter for binomial family taken to be 1) >> >> Null deviance: 491.84 on 376 degrees of freedom >> Residual deviance: 371.78 on 375 degrees of freedom >> AIC: 375.78 >> >> Number of Fisher Scoring iterations: 6 >> >> >> >> My question is that the coefficient of the independent variable (log-odds) >> at 4.4738 is difficult to interpret. I have obtained the exponent of the >> coefficient below and as the result of 87.69.. shown below shows, the >> number is high which makes suspicious that there is something not working >> right. >> >> >> >>> exp(coef(divgress)) >> (Intercept) PRFD >> 0.03508772 87.69230769 >>> >> >> >> >> The dataset is attached. I appreciate your help. >> >> >> >> >> This email communication is confidential and may be privileged or otherwise >> protected. It is intended exclusively for those individuals and entities >> addressed above and any other persons who have been specifically authorised >> to receive it. You should not copy it or disclose its contents to anyone. If >> you are not such an intended recipient, please notify us that you have >> received this email in error. Please then delete the email and any >> attachments and destroy any copies of it. We regret any inconvenience >> resulting from erroneous delivery of this message and thank you for your >> cooperation. >> Please note that none of the Supreme Committee for Delivery and Legacy or >> any of its affiliated entities will have any liability for any incorrect or >> incomplete transmission of the information contained in this email nor for >> any delay in its receipt. Emails are not secure and cannot be guaranteed to >> be error free. Anyone who communicates with us by email is taken to accept >> these risks. Any views or opinions expressed in this email are solely those >> of the author and do not necessarily represent those of the Supreme >> Committee for Delivery and Legacy or any of its affiliated entities. Any >> logo trademark or other intellectual property forming part of or attached to >> this email belongs exclusively to the Supreme Committee for Delivery and >> Legacy. Any unauthorised reproduction copying or other use by you or others >> is strictly prohibited. >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2015.0.5645 / Virus Database: 4281/9067 - Release Date: 02/06/15 >> >> >> > > -- > Michael > http://www.dewey.myzen.co.uk > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
