Toxicology data
A toxicologist wonders if exposure to a chemical increases mortality as its dose increases. She has exposed test organisms to different doses of a chemical and recorded the number that died in each test tank. Each dose was repeated on three different days.
First, build a GLM. Building a simple model makes debugging easier. Also, you will later compare the results to GLMER. This model includes dose and replicate as a fixed-effects.
Second, build a GLMER. This time, dose is a fixed-effect and replicate is a random-effects intercept.
Last, examine the coefficient estimates with coef() from each model. Notice how the intercept estimates are displayed differently from each model.
This exercise is part of the course
Hierarchical and Mixed Effects Models in R
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Fit glm_out and look at its coefficient estimates
glm_out <- glm(___ ~ ___ + ___,
family = "___", data = df)
coef(___)