Decoding mixed model equations using LMMonBoard
High-throughput Phenotyping Driven Quantitative Genetics @CMA-FCT-NOVA
Background
This is the day 1 computer lab session for quantitative genetic analysis. The goal of this exercise is to understand mixed model equations (MME) using an interactive MME visualization tool LMMonBoard.
Exercise 1
- Select
Blank Example
from theData
drop-down list. - In
Model equation
, remove+ X2 + X5
so that you haveY1 = Animal + X1
. - In the
Fixed / Random Effects
column, selectAnimal
from theRandom Effects (i.i.d.)
drop-down list. - Click
Update LMM Results
on the right upper corner.
Assume that the residual variance \(\sigma^2_e = 1\) and the additive genetic variance \(\sigma^2_g = 1\).
Questions
- How many fixed effects are in the model? How many levels?
- How many random effects are in the model? How many levels?
- Interpret each component of MME.
Exercise 2
- In
Model equation
, add+ X2
so that you haveY1 = Animal + X1 + X2
. - In the
Fixed / Random Effects
column, selectAnimal
from theRandom Effects (i.i.d.)
drop-down list. - Click
Update LMM Results
on the right upper corner.
Questions
- How many fixed effects are in the model? How many levels?
- How many random effects are in the model? How many levels?
- Interpret each component of MME.
Exercise 3
- In the
Fixed / Random Effects
column, selectAnimal
from theRandom Effects (Correlated)
drop-down list. - Click
Update LMM Results
on the right upper corner.
Questions
- How many fixed effects are in the model? How many levels?
- How many random effects are in the model? How many levels?
- Interpret each component of MME.
Exercise 4
- In
Model equation
, add+ X5
so that you haveY1 = Animal + X1 + X2 + X5
. - In the
Fixed / Random Effects
column, selectAnimal
from theRandom Effects (Correlated)
drop-down list. - In the
Continuous / Categorical Variables
column, selectX5
from theContinuous
drop-down list. - Click
Update LMM Results
on the right upper corner.
Questions
- How many fixed effects are in the model? How many levels?
- How many random effects are in the model? How many levels?
- Interpret each component of MME.