15.6 Hierarchical data

• Cherry Blossom data presents a new challenge: Hierachical data.

• Hierarchical structure - each group is unique but also connected. Common structure:

  • Groups could be schools and observations students within each school

  • Groups could be labs, observations multiple experiments in each lab

  • Groups could be subjects, observations are a series of tests (Exercise 15.3ff)

• Middle ground between complete and no pooling: Partial pooling.

• Provides insight into both

  1. Within-group variability

  2. Between-group variability