Binomial data

Hierarchical and Mixed Effects Models in R

Richard Erickson

Data Scientist

Examples of binomial data

• Coin/toss
• Yes/No
• Dead/alive
• Behavior
• Choice
• Study result

Binomial data with glmer

glmer(y ~ x + (1 | group), family = "error term")

Dose-response case study

• Study had increasing dose
• Repeated in triplicate
• Requires glmer(), not glm()

Internet purchase

• "Purchases" or "Pass"
• "ranking" of product 0 to 20
• "friend recommendation"
• Tracked sales with 4 focal groups in different "cities"
• Do friend recommendations help?

Odds-ratio

• Regression coefficients hard to explain
• Odds-ratios sometimes easier
• If Group A has odds-ratio of 2.0 $\times$, 2:1 A will do something compared to the other group
• Extract by exponentiation logistic coefficients
• exp(coef(modelOut))

Let's practice!

Hierarchical and Mixed Effects Models in R