18 - Factor Analysis Flashcards
Factor analysis
Places together closely related items for a theoretical concept. It seeks to discover if the observed variables can be explained in terms of much smaller number of super-variables.
- EFA
- CFA
Factor loading should be at least 0.3
Explanatory factor analysis
large data sets of multiple variables with smala factors thereby identifying factor structure
Confirmatory factor analysis
Aims to confirm theoretical predictions = hypothesis testing.
Principal component analysis
As there are an infinite nb if equally accurate factors, researcher requires a tool that chooses the most appropriate.
In EFA is used for data reduction or determining the set of items that hang together.
PCA assumptions
- large sample (x5 or 10 variables)
- normal variables
- linear relation between variables
- absence of outliers
- interval data
Communality
Sum of squared loading factors
Eigenvalue
Illustrates the amount of common variance explained by a factor.
Sum of squared loading factors of the factor.
Variance extracted
Eigenvalue*100%/nb ouf factors
Factors issues
- naming
- selection of factors (kaiser’s rule >1 or scree test) not the only one possible
Factor analysis steps
- descriptive and correlation matrix
- PCA gives an estimate of the loadings
- factors are rotated (varimax)
- interpretation