Factor Analysis Flashcards
What is a factor analysis?
- Identify psychological constructs from a scale
Are they driven by the same underlying factor? - Reduce the number of variables in a data set
Representations of themes or constructs
What are the different types of factor analysis?
- Principal component analysis (focus)
New measurement - Exploratory factor analysis
Questions that tap into the same factor or factors, ask if they have the same underlying concept - Confirmatory factor analysis
Adapting to new context or new language
What is needed to do before factor analysis can begin?
- Check correlation
Needs to be reasonable between items - Multicollinearity
If any item is over r=+.90
-Singularity
Perfect correlation
What tests need to be included in factor analysis?
- Kaiser-Meyer-Olkin
Compact association, distinct and reliable factor
Should be .50, pref over .80
How well suited the items are for factor analysis - Bartlett’s test of sphericity
Do we have good correlation among scale items?
Should be significant= decent correlation
Factor Analysis - SPSS output
Table 1
- Correlation between scale items
Table 2
- KMO and Bartlett’s Test
Table 3
- Information about proportion of common variance in a variable
- 0 = has a unique variance
- 1 = share variance with others
- Extraction= to make conclusions, % overlap with overall variation of the other items
Table 4
- Decide how many factors our scale is composed of (extraction)
- Eigenvalue = variation explained by a factor
- Retain all factors greater than 1
Table 5
- Scree plot; how many factors we should retain
- Find point inflextion, drastic change in slope
- Retain factors on the left side of point inflextion
Table 7
- Info of which items makes up a factor
- Conventional cut off for factor loadings .30
Table 8
- Info of correlation between factors
Factor Analysis - APA style
- What we performed
- How many items
- How many factors
Eigenvalues - Explained variation from factors
- How many items in each factor, their loading range
- Inter-item reliability for each factor
- Conclusion
What is item-scale correlations?
How different each scale is to the factor