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I have a binomial model with a 3-way interaction:

> all.fit <-  glm(cbind(Presence, Total-Presence) ~ 
                  Season*ToD*Site, family = binomial, 
                  data = all.dt)
> summary(all.fit)

Call: glm(formula = cbind(Presence, Total - Presence) ~ Season * ToD * Site, family = binomial, data = all.dt)

Deviance Residuals: Min 1Q Median 3Q Max
-6.0379 -1.3245 -0.6221 0.3961 8.6824

Coefficients: Estimate Std. Error z value Pr(>|z|)
(Intercept) -4.66074 0.26852 -17.357 < 2e-16 *** SeasonSpring 0.60478 0.33133 1.825 0.067959 .
SeasonSummer -0.82682 0.48901 -1.691 0.090873 .
SeasonWinter 1.26868 0.30149 4.208 2.58e-05 *** ToDDay 0.09865 0.31530 0.313 0.754381
ToDDusk 2.48420 0.28183 8.814 < 2e-16 *** ToDNight 2.65294 0.27185 9.759 < 2e-16 *** SiteKawau 3.09495 0.27605 11.212 < 2e-16 *** SiteNoises 3.48048 0.27479 12.666 < 2e-16 *** SiteTawharanui 2.94694 0.27684 10.645 < 2e-16 *** SiteTiritiri 3.21127 0.27557 11.653 < 2e-16 *** SeasonSpring:ToDDay 0.90540 0.37560 2.411 0.015928 *
SeasonSummer:ToDDay 2.16685 0.52151 4.155 3.25e-05 *** SeasonWinter:ToDDay -0.12465 0.35416 -0.352 0.724863
SeasonSpring:ToDDusk -2.78750 0.40957 -6.806 1.00e-11 *** SeasonSummer:ToDDusk -1.52114 0.55644 -2.734 0.006263 ** SeasonWinter:ToDDusk -0.90286 0.32121 -2.811 0.004941 ** SeasonSpring:ToDNight -1.66162 0.34346 -4.838 1.31e-06 *** SeasonSummer:ToDNight -1.85826 0.51861 -3.583 0.000339 *** SeasonWinter:ToDNight -0.21758 0.30592 -0.711 0.476946
SeasonSpring:SiteKawau -0.67217 0.34426 -1.953 0.050875 .
SeasonSummer:SiteKawau 1.24760 0.49690 2.511 0.012047 *
SeasonWinter:SiteKawau -1.68237 0.31709 -5.306 1.12e-07 *** SeasonSpring:SiteNoises -0.79023 0.34223 -2.309 0.020940 *
SeasonSummer:SiteNoises 0.42570 0.49791 0.855 0.392560
SeasonWinter:SiteNoises -0.73055 0.31139 -2.346 0.018972 *
SeasonSpring:SiteTawharanui -0.25773 0.34405 -0.749 0.453794
SeasonSummer:SiteTawharanui 1.32456 0.49760 2.662 0.007770 ** SeasonWinter:SiteTawharanui -0.51055 0.31368 -1.628 0.103604
SeasonSpring:SiteTiritiri -0.48838 0.34274 -1.425 0.154178
SeasonSummer:SiteTiritiri 0.93694 0.49749 1.883 0.059656 .
SeasonWinter:SiteTiritiri -1.27870 0.31406 -4.072 4.67e-05 *** ToDDay:SiteKawau 0.70933 0.32351 2.193 0.028335 *
ToDDusk:SiteKawau -2.35320 0.29549 -7.964 1.67e-15 *** ToDNight:SiteKawau -5.33351 0.29943 -17.812 < 2e-16 *** ToDDay:SiteNoises 0.27852 0.32258 0.863 0.387906
ToDDusk:SiteNoises -2.53814 0.29389 -8.636 < 2e-16 *** ToDNight:SiteNoises -4.04432 0.28257 -14.313 < 2e-16 *** ToDDay:SiteTawharanui -0.16455 0.32550 -0.506 0.613193
ToDDusk:SiteTawharanui -2.76975 0.29927 -9.255 < 2e-16 *** ToDNight:SiteTawharanui -2.62701 0.28227 -9.307 < 2e-16 *** ToDDay:SiteTiritiri 0.77569 0.32307 2.401 0.016350 *
ToDDusk:SiteTiritiri -2.27149 0.29441 -7.715 1.21e-14 *** ToDNight:SiteTiritiri -4.15841 0.28495 -14.593 < 2e-16 *** SeasonSpring:ToDDay:SiteKawau -0.19831 0.38943 -0.509 0.610596
SeasonSummer:ToDDay:SiteKawau -1.61316 0.53079 -3.039 0.002372 ** SeasonWinter:ToDDay:SiteKawau 0.57193 0.37047 1.544 0.122635
SeasonSpring:ToDDusk:SiteKawau 2.48229 0.43071 5.763 8.25e-09 *** SeasonSummer:ToDDusk:SiteKawau 1.37786 0.56992 2.418 0.015622 *
SeasonWinter:ToDDusk:SiteKawau 0.81702 0.34933 2.339 0.019347 *
SeasonSpring:ToDNight:SiteKawau 1.41405 0.40613 3.482 0.000498 *** SeasonSummer:ToDNight:SiteKawau 2.06227 0.54597 3.777 0.000159 *** SeasonWinter:ToDNight:SiteKawau 0.08689 0.36989 0.235 0.814279
SeasonSpring:ToDDay:SiteNoises -0.28007 0.38782 -0.722 0.470188
SeasonSummer:ToDDay:SiteNoises -1.48112 0.53201 -2.784 0.005369 ** SeasonWinter:ToDDay:SiteNoises -0.06044 0.36566 -0.165 0.868708
SeasonSpring:ToDDusk:SiteNoises 1.93847 0.43143 4.493 7.02e-06 *** SeasonSummer:ToDDusk:SiteNoises 0.63232 0.57685 1.096 0.273006
SeasonWinter:ToDDusk:SiteNoises 0.83278 0.34003 2.449 0.014321 *
SeasonSpring:ToDNight:SiteNoises 0.69621 0.37365 1.863 0.062422 .
SeasonSummer:ToDNight:SiteNoises 0.06911 0.55930 0.124 0.901655
SeasonWinter:ToDNight:SiteNoises 0.48690 0.32194 1.512 0.130428
SeasonSpring:ToDDay:SiteTawharanui -0.23150 0.39050 -0.593 0.553287
SeasonSummer:ToDDay:SiteTawharanui -1.96624 0.53250 -3.692 0.000222 *** SeasonWinter:ToDDay:SiteTawharanui 0.43487 0.36870 1.179 0.238216
SeasonSpring:ToDDusk:SiteTawharanui 2.04614 0.43633 4.689 2.74e-06 *** SeasonSummer:ToDDusk:SiteTawharanui 0.59597 0.57680 1.033 0.301491
SeasonWinter:ToDDusk:SiteTawharanui 0.73280 0.34653 2.115 0.034456 *
SeasonSpring:ToDNight:SiteTawharanui 1.02467 0.36109 2.838 0.004544 ** SeasonSummer:ToDNight:SiteTawharanui 1.19957 0.52990 2.264 0.023589 *
SeasonWinter:ToDNight:SiteTawharanui -0.16571 0.32155 -0.515 0.606306
SeasonSpring:ToDDay:SiteTiritiri -0.49278 0.38807 -1.270 0.204143
SeasonSummer:ToDDay:SiteTiritiri -1.63113 0.53142 -3.069 0.002145 ** SeasonWinter:ToDDay:SiteTiritiri 0.37405 0.36773 1.017 0.309069
SeasonSpring:ToDDusk:SiteTiritiri 1.81283 0.43042 4.212 2.53e-05 *** SeasonSummer:ToDDusk:SiteTiritiri 0.83455 0.57225 1.458 0.144744
SeasonWinter:ToDDusk:SiteTiritiri 0.50070 0.34463 1.453 0.146263
SeasonSpring:ToDNight:SiteTiritiri 1.49159 0.36761 4.057 4.96e-05 *** SeasonSummer:ToDNight:SiteTiritiri 1.30689 0.53796 2.429 0.015127 *
SeasonWinter:ToDNight:SiteTiritiri 0.79478 0.32728 2.428 0.015164 *


Signif. codes: 0 ‘*’ 0.001 ‘’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

(Dispersion parameter for binomial family taken to be 1)

Null deviance: 104046  on 22997  degrees of freedom

Residual deviance: 62740 on 22918 degrees of freedom AIC: 86778

Number of Fisher Scoring iterations: 6

I have reported the significance of the three way interaction. And now I want to do some comparisons, for example, say Winter at one Site had a higher proportion than Winter at another site. Can I do this following the example here, by changing the level order? (https://rpubs.com/raoulbia/interpreting_glm_logistic_regression_output)

enter image description here

  • 1
    Which events are you counting? This looks like binomial data, so use the format with cbind. If your response is a fraction, some call that a fractional outcome logit see https://stats.stackexchange.com/questions/530149/help-with-needed-with-fractional-outcomes-logit-regression quasibinomial uses quasilikelihood estimation, which does not use directly a binomial likelihood. See https://stats.stackexchange.com/questions/216122/what-is-the-difference-between-logistic-regression-and-fractional-response-regre, and ... ' – kjetil b halvorsen Jun 27 '21 at 23:51
  • ... https://stats.stackexchange.com/questions/418832/why-the-absence-of-probability-distribution-for-using-quasi-likelihood – kjetil b halvorsen Jun 27 '21 at 23:51
  • First make a general test of fhe highest-order interaction, that is, compare a model with interactions of order 3 to a model with only interactions of order 2 – kjetil b halvorsen Jun 28 '21 at 03:11
  • Are you talking about choosing the most parsimonious model? Is it possible to answer the question with the existing model? – Louise Wilson Jun 28 '21 at 03:20
  • 1
    You can do it, and it is not necessary to change order of levels. What you want to do is test some contrasts, which can be cumbersome in base R when there are interactions. The library on CRAN car have the function linearHypothesis see https://stats.stackexchange.com/questions/211584/testing-linear-restriction-in-r/211597#211597 making this easier, but you will have to read its help page – kjetil b halvorsen Jun 28 '21 at 03:27
  • Thanks! I'll take a look – Louise Wilson Jun 28 '21 at 03:29

1 Answers1

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You might benefit from the tools L. Hawyard-Smith put together for looking at interactions in count data. https://github.com/lindesaysh/MRSea/blob/master/inst/docs/UsingMRSea_v1.3.pdf