fix for glm

Author: strengejacke

R/format.R

@@ -838,7 +838,9 @@ equivalence_columns <- c(
   # estimate name
   if (is.null(predict_type)) {
     estimate_name <- "Mean"
-  } else if (!is.null(predict_type) && tolower(predict_type) %in% .brms_aux_elements()) {
+  } else if (predict_type == "context") {
+    estimate_name <- "Estimate"
+  } else if (tolower(predict_type) %in% .brms_aux_elements()) {
     # for Bayesian models with distributional parameter
     estimate_name <- tools::toTitleCase(predict_type)
   } else if (

R/get_contexteffects.R

@@ -1,13 +1,24 @@
 # special contrasts: context effects ----------------------------------------
 # ---------------------------------------------------------------------------
 
-get_contexteffects <- function(model, my_args, ci, ...) {
-  out <- marginaleffects::avg_comparisons(
-    model,
-    variables = my_args$contrast,
-    hypothesis = my_args$comparison,
-    ...
-  )
+get_contexteffects <- function(model, my_args, model_info, ...) {
+  if (model_info$is_linear) {
+    out <- marginaleffects::avg_comparisons(
+      model,
+      variables = my_args$contrast,
+      hypothesis = my_args$comparison,
+      ...
+    )
+  } else {
+    out <- marginaleffects::avg_comparisons(
+      model,
+      variables = my_args$contrast,
+      hypothesis = my_args$comparison,
+      type = "link",
+      transform = "exp",
+      ...
+    )
+  }
   # save some labels for printing
   attr(out, "by") <- my_args$by
   attr(out, "contrast") <- my_args$contrast

R/get_marginalcontrasts.R

@@ -102,8 +102,8 @@ get_marginalcontrasts <- function(
     )
     predict <- "response"
   } else if (isTRUE(my_args$context_effects)) {
-    out <- get_contexteffects(model, my_args, ci, ...)
-    predict <- "response"
+    out <- get_contexteffects(model, my_args, model_info, ...)
+    predict <- "context"
   } else if (compute_slopes) {
     # sanity check - contrast for slopes only makes sense when we have a "by" argument
     if (is.null(my_args$by)) {

tests/testthat/test-estimate_contrasts_context.R

@@ -4,7 +4,7 @@ skip_on_os("mac")
 skip_if(getRversion() < "4.5.0")
 skip_if_not_installed("datawizard")
 
-test_that("estimate_contrast, context effects", {
+test_that("estimate_contrast, context effects, linear", {
   data(penguins, package = "datasets")
   d <- datawizard::demean(penguins, "bill_len", by = "species")
   m <- lm(bill_dep ~ bill_len_between + bill_len_within, data = d)
@@ -20,3 +20,20 @@ test_that("estimate_contrast, context effects", {
   expect_equal(out$Mean, b[1] - b[2], tolerance = 1e-4, ignore_attr = TRUE)
   expect_equal(out$SE, sqrt((se[1]^2 + se[2]^2)), tolerance = 1e-4, ignore_attr = TRUE)
 })
+
+test_that("estimate_contrast, context effects, linear", {
+  data(penguins, package = "datasets")
+  d <- datawizard::demean(penguins, "bill_len", by = "species")
+  d$out <- datawizard::categorize(d$flipper_len) - 1
+  m <- glm(out ~ bill_len_between + bill_len_within, data = d, family = binomial())
+
+  b <- coef(summary(m))[2:3, 1]
+  se <- coef(summary(m))[2:3, 2]
+
+  out <- modelbased::estimate_contrasts(
+    m,
+    c("bill_len_between", "bill_len_within"),
+    comparison = "context"
+  )
+  expect_equal(out$Estimate, exp(b[1] - b[2]), tolerance = 1e-4, ignore_attr = TRUE)
+})