WK 7 Flashcards
What does a path model allow us to do?
A path model allows us to test several linear models together as a set
What are exogenous variables?
They are essentially independent variables
What are endogenous variables?
They are dependent variables in at least one part of the model
What directions do the arrows go in exogenous variables?
Only have directed arrows going out (basically predictors)
What directions do the arrows go in endogenous variables?
They have directed arrows going in
In a diagram, what does a square represent?
It represents an observed/measured variable
In a diagram, what does a circle represent?
It represents an unobserved/latent variable
In a diagram, what does a two-headed arrow represent?
It represents covariance
In a diagram, what does a single headed arrow represent?
It represents a regression path
In a diagram, when there is a single arrow, what is it showing?
The square that the arrow is pointing in to is the dependent variable/outcome, whereas the other side is the predictor
What does every endogenous variable have?
They have a residual
What do you need after you run a lavaan model?
you need to use a summary function
What is specification in path models?
It concerns which variables relate to which others, and in what ways
What are the standard rules in path models?
- all exogenous variables correlate
- for endogenous variables, we correlate the residuals, not the variables
- endogenous variable residuals do not correlate with exogenous variables
- all paths are recursive (i.e. we cannot have loops like A-> B, B-> A)
What is model identification?
Identification concerns the number of knowns versus unknowns
In order to test our model, what do we need?
We need more knowns than unknowns in order to test our model
What are the knowns?
The knowns are variances and covariances
What are path models based on?
path models are based on the correlation matrix between variables that you have measured
What are the unknowns?
The unknowns are the parameters we want to estimate