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Psychology 202b Advanced Psychological Statistics, II. March 31 , 2011. Path Analysis. Path analysis: Fundamental theorem Vocabulary review Examples. Path Analysis.
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Psychology 202bAdvanced Psychological Statistics, II March 31, 2011
Path Analysis • Path analysis: • Fundamental theorem • Vocabulary review • Examples
Path Analysis • The fundamental theorem: “The correlation between two variables X and Z is equal to the sum of the product of all paths from each possible tracing between X and Z. The tracings include all possible routes between X and Z, with the exceptions that (1) the same variable is not entered twice per tracing and (2) a variable is not both entered and exited through an arrowhead.” (Keith, p. 215)
Path Analysis • More generally, the same idea works when coefficients are unstandardized (in which case, the total path is no longer a correlation).
Some Vocabulary • Exogenous variables are variables that only have paths leading away from them. • Endogenous variables also have paths leading into them. • Recursive models have no paths with bidirectional flow. • A saturated recursive model is one in which all possible recursive paths are present.
Examples • A saturated recursive model. • A nonsaturated recursive model. • The idea of overidentification and the problem of model fit.
Next time • Making things easier with SEM.