```
# NOT RUN {
fit <- brm(count ~ log_Age_c + log_Base4_c * Trt + (1 | patient),
data = epilepsy, family = poisson())
## plot all marginal effects
plot(marginal_effects(fit), ask = FALSE)
## change colours to grey scale
me <- marginal_effects(fit, "log_Base4_c:Trt")
plot(me, plot = FALSE)[[1]] +
scale_color_grey() +
scale_fill_grey()
## only plot the marginal interaction effect of 'log_Base4_c:Trt'
## for different values for 'log_Age_c'
conditions <- data.frame(log_Age_c = c(-0.3, 0, 0.3))
plot(marginal_effects(fit, effects = "log_Base4_c:Trt",
conditions = conditions))
## also incorporate random effects variance over patients
## also add data points and a rug representation of predictor values
plot(marginal_effects(fit, effects = "log_Base4_c:Trt",
conditions = conditions, re_formula = NULL),
points = TRUE, rug = TRUE)
## change handling of two-way interactions
int_conditions <- list(
log_Base4_c = setNames(c(-2, 1, 0), c("b", "c", "a"))
)
marginal_effects(fit, effects = "Trt:log_Base4_c",
int_conditions = int_conditions)
marginal_effects(fit, effects = "Trt:log_Base4_c",
int_conditions = list(log_Base4_c = quantile))
## fit a model to illustrate how to plot 3-way interactions
fit3way <- brm(count ~ log_Age_c * log_Base4_c * Trt, data = epilepsy)
conditions <- data.frame(log_Age_c = c(-0.3, 0, 0.3))
rownames(conditions) <- paste("log_Age_c =", conditions$log_Age_c)
marginal_effects(
fit3way, "log_Base4_c:Trt", conditions = conditions
)
## only include points close to the specified values of log_Age_c
me <- marginal_effects(
fit3way, "log_Base4_c:Trt", conditions = conditions,
select_points = 0.1
)
plot(me, points = TRUE)
# }
# NOT RUN {
# }
```

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