6 Structural Equation Modelling Flashcards
What is the aim of path analysis?
To estimate the magnitude and significance of hypothesised causal connections between variables.
What is the path coefficient for a residual term? And why?
Always 1. It is assumed that error is not systematically associated with anything else.
In path analysis, what is disturbance?
Error/residual
What are endogenous variables? How do they work with arrows?
Presumed effects. Have arrows going into them.
What are exogenous variables? How do they work with arrows?
Presumed causes. Variables WITHOUT arrows going into them. Arrows go from them to other causes.
What is a path coefficient?
Value of the arrow/estimate of cause.
How many regression equations per endogenous variable do you need in a path model?
1
How do you calculate indirect effects?
By multiplying the path coefficients.
How do you calculate total effects?
Adding direct and indirect effects.
What’s the difference between recursive and non-recursive models?
Recursive – all paths go in one direction with no feedback loops. Can be solved with standard multiple regression equations.
Non-recursive –have reciprocal causality/feedback loops. Cannot be solved with regression equations.
What’s the difference between:
1) just-identified
2) under-identified
3) over-identified models?
1) Under-identified models have less than one possible solutions (i.e. they cannot be solved).
2) Just-identified – there is only one solution to what paths are.
3) Over-identified –have more than one solution. SEM programs determine which is most likely (e.g. CFA models which are rotated for best fit).
A just-identified (saturated) model has __ ___ elements in the covariance matrix as there are ________ __ __ _______.
A just-identified (saturated) model has as many elements in the covariance matrix as there are parameters to be estimated.
In an underidentified model there are more or less elements in the correlation matrix than there are parameters to be estimated?
Underidentified - less elements in the correlation matrix than there are parameters to be estimated.
How do you calculate the number of elements in the correlation matrix if the number of variables is greater than 3?
Use the formula for triangular numbers.
K= (N(N+1)) / 2
In an underestimated model in SEM, df is _______.
In an underestimated model in SEM, df is negative.
