Dear Petr, thank you very much for your feedback. Can anyone in the list advise me if the way I report the results is correct?
Kind regards FJ On Mon, Nov 12, 2018 at 1:02 PM PIKAL Petr <petr.pi...@precheza.cz> wrote: > Hi Frodo > > > > I do not consider myself as an arbiter in statistical results and their > presentation. Again your text seems to as good as any other. > > > > You should keep responses to mailing list as others could have another > opinion. > > > > Cheers > > Petr > > > > > > *From:* Frodo Jedi <frodojedi.mailingl...@gmail.com> > *Sent:* Monday, November 12, 2018 1:48 PM > *To:* PIKAL Petr <petr.pi...@precheza.cz> > *Subject:* Re: [R] Reporting binomial logistic regression from R results > > > > Dear Petr, > > many thanks for your reply. I was wondering whether in your opinion it is > correct to report in a journal the following text: > > > > > > “A logistic regression was performed to ascertain the effects of the > system type on the likelihood that participants report correct > identifications. The logistic regression model was statistically > significant, χ2(3) = 354.6, p < 0.001, indicating an overall effect of the > system type on participants' identification performances. The Wald test was > used to compare the model coefficients related to the three systems. > Results showed that participants’ accuracy was significantly lower for the > system B compared to both the system C (χ2(1) = 22.3, p < 0.001) and the > system A (χ2(1) = 58.7, p < 0.001), as well as that the system C led to > significantly higher identification accuracies than the system A (χ2(1) = > 12, p < 0.001).” > > > > > > Best wishes > > > > FJ > > > > > > > > > > > > On Mon, Nov 12, 2018 at 10:05 AM PIKAL Petr <petr.pi...@precheza.cz> > wrote: > > Dear Frodo (or Jedi) > > The results seems to confirm your assumption that 3 systems are different. > How you should present results probably depends on how it is usual to > report such results in your environment. > > BTW. It seems to me like homework and this list has no homework policy > (Sorry, if I am mistaken). > > Cheers > Petr > > -----Original Message----- > > From: R-help <r-help-boun...@r-project.org> On Behalf Of Frodo Jedi > > Sent: Monday, November 12, 2018 2:08 AM > > To: r-help@r-project.org > > Subject: [R] Reporting binomial logistic regression from R results > > > > Dear list members, > > I need some help in understanding whether I am doing correctly a binomial > > logistic regression and whether I am interpreting the results in the > correct way. > > Also I would need an advice regarding the reporting of the results from > the R > > functions. > > > > I want to report the results of a binomial logistic regression where I > want to > > assess difference between the 3 levels of a factor (called System) on the > > dependent variable (called Response) taking two values, 0 and 1. My goal > is to > > understand if the effect of the 3 systems (A,B,C) in System affect > differently > > Response in a significant way. I am basing my analysis on this URL: > > https://stats.idre.ucla.edu/r/dae/logit-regression/ > > > > This is the result of my analysis: > > > > > fit <- glm(Response ~ System, data = scrd, family = "binomial") > > > summary(fit) > > > > Call: > > glm(formula = Response ~ System, family = "binomial", data = scrd) > > > > Deviance Residuals: > > Min 1Q Median 3Q Max > > -2.8840 0.1775 0.2712 0.2712 0.5008 > > > > Coefficients: > > Estimate Std. Error z value Pr(>|z|) > > (Intercept) 3.2844 0.2825 11.626 < 2e-16 *** > > SystemB -1.2715 0.3379 -3.763 0.000168 *** > > SystemC 0.8588 0.4990 1.721 0.085266 . > > --- > > Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 > > > > (Dispersion parameter for binomial family taken to be 1) > > > > Null deviance: 411.26 on 1023 degrees of freedom Residual deviance: > > 376.76 on 1021 degrees of freedom > > AIC: 382.76 > > > > Number of Fisher Scoring iterations: 6 > > Following this analysis I perform the wald test in order to understand > whether > > there is an overall effect of System: > > > > library(aod) > > > > > wald.test(b = coef(fit), Sigma = vcov(fit), Terms = 1:3) > > Wald test: > > ---------- > > > > Chi-squared test: > > X2 = 354.6, df = 3, P(> X2) = 0.0 > > The chi-squared test statistic of 354.6, with 3 degrees of freedom is > associated > > with a p-value < 0.001 indicating that the overall effect of System is > statistically > > significant. > > > > Now I check whether there are differences between the coefficients using > again > > the wald test: > > > > # Here difference between system B and C: > > > > > l <- cbind(0, 1, -1) > > > wald.test(b = coef(fit), Sigma = vcov(fit), L = l) > > Wald test: > > ---------- > > > > Chi-squared test: > > X2 = 22.3, df = 1, P(> X2) = 2.3e-06 > > > > > > > > # Here difference between system A and C: > > > > > l <- cbind(1, 0, -1) > > > wald.test(b = coef(fit), Sigma = vcov(fit), L = l) > > Wald test: > > ---------- > > > > Chi-squared test: > > X2 = 12.0, df = 1, P(> X2) = 0.00052 > > > > > > > > # Here difference between system A and B: > > > > > l <- cbind(1, -1, 0) > > > wald.test(b = coef(fit), Sigma = vcov(fit), L = l) > > Wald test: > > ---------- > > > > Chi-squared test: > > X2 = 58.7, df = 1, P(> X2) = 1.8e-14 > > > > My understanding is that from this analysis I can state that the three > systems > > lead to a significantly different Response. Am I right? If so, how > should I report > > the results of this analysis? What is the correct way? > > > > > > Thanks in advance > > > > Best wishes > > > > FJ > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > 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. > Osobní údaje: Informace o zpracování a ochraně osobních údajů obchodních > partnerů PRECHEZA a.s. jsou zveřejněny na: > https://www.precheza.cz/zasady-ochrany-osobnich-udaju/ | Information > about processing and protection of business partner’s personal data are > available on website: > https://www.precheza.cz/en/personal-data-protection-principles/ > Důvěrnost: Tento e-mail a jakékoliv k němu připojené dokumenty jsou > důvěrné a podléhají tomuto právně závaznému prohláąení o vyloučení > odpovědnosti: https://www.precheza.cz/01-dovetek/ | This email and any > documents attached to it may be confidential and are subject to the legally > binding disclaimer: https://www.precheza.cz/en/01-disclaimer/ > > [[alternative HTML version deleted]] ______________________________________________ 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.
