Exploratory Factor Analysis Flashcards
What is an exploratory factor analysis (EFA)?
Approach to decrease the number of measures into a smaller set
What does EFA usually rely on?
A mathematical technique called Principle Component Analysis (PCA)
What does PCA do?
it determines factors that can explain the original set of measures based on patterns of correlations
Usually assumed that resulting factors are___
uncorrelated
The factors that are determined are based on idea of common process that influences multiple measures.
Factors are NOT directly ____?
measured or observed
What does the EFA process involve?
Pre-analysis checks and Extracting factors
What does pre-analysis process of EFA involve?
Variability, Communality, Correlation matrix, sufficient data and sample size.
How do you determine how many factors to extract?
3 rules:
K1 rule
Scree test
Parallel analysis
What are eigenvalues?
a measure of the variance explained by a factor
What is the K1 rule?
Select all factors with eigenvalues >1
What is the Scree test?
Plot the eigenvalues against the component number
What is parallel analysis?
Generate a set of random eigenvalues given N(number of ppts) and P(number of items).
Extract as many factors as there are observed eigenvalues greater than the random eigenvalues
What are the 2 types of rotation?
orthogonal and oblique
Which type of rotation assumes that the factors are NOT correlated with each other?
orthogonal e.g varimax
Which type of rotation assumes that the factors are correlated with each other?
oblique e.g direct oblimin
