8 Random Environmental Effects

Learning Objectives

By the end of this chapter, you will be able to:

Distinguish permanent from temporary environmental effects
Define repeatability and state its relationship to heritability
Set up and solve a repeatability model with multiple records per animal
Model a common environmental (litter) effect and explain its confounding with relationship
Interpret variance ratios when several random effects compete for the same variance

Assumes Ch 6.

Chapter in progress

This chapter has not been written yet. The objectives above are the contract it will be written against — they are taken from CHAPTERS.md, which is the outline for the whole book.

Purpose. Repeatability and common environmental effects — a second random effect that is not genetic.

---
title: "Random Environmental Effects"
---

::: {.callout-note icon=false}
## Learning Objectives

By the end of this chapter, you will be able to:

1. **Distinguish** permanent from temporary environmental effects
2. **Define** repeatability and state its relationship to heritability
3. **Set** up and solve a repeatability model with multiple records per animal
4. **Model** a common environmental (litter) effect and explain its confounding with relationship
5. **Interpret** variance ratios when several random effects compete for the same variance
:::

*Assumes Ch 6.*

::: {.callout-warning}
## Chapter in progress

This chapter has not been written yet. The objectives above are the contract it will be written
against — they are taken from `CHAPTERS.md`, which is the outline for the whole book.

**Purpose.** Repeatability and common environmental effects — a second random effect that is not genetic.
:::