Factor Analysis Flashcards
The amount of variance shared by each VARIABLE with the others is technically called
communality
The amount of variance accounted by each FACTOR is technically represented by the mathematical concept of an
EIGENVALUE
SPSS will automatically extract those factors with variance greater than ??? if no specific criteria is specified.
1
This criteria makes sense if we remeber that all the input variables should be ???? to ensure a mean = 0 and a standard deviation = 1.
standardize
Once the factors are extracted, we will interpret their meaning by exploring the ??? matrix.
Component
Coefficients in this matrix can be understood as ??? coefficients between Factors and Input Variables.
Correlation
If the interpretation is not straightforward, we can use a factor ??? to better interpret Factors.
Rotation
Among the different types available, Varimax keeps the property of ??? so the new factors will still being independent.
Ortogonality]
Once the interpretation is clear, we can save factor values, technically called factor ??? in our dataset.
Scores
The set of input variables for a FACTOR ANALYSIS should exhibit a low degree of redundancy
FALSE. Redundancy is, in fact, essential for a good factor analysis.
Orthogonality of factors is not necessarily a realistic assumption
TRUE. Sometimes, independency=orthogonality is not realistic and we find more credible some degree of correlation / overlapping between factors.
If input variables were orthogonal, then a factor analysis would not make sense
TRUE. If original variables are orthogonal, that means no correlation between them and thus no space for common factors.
Standard/Classic factor analysis is suitable mainly for metric variables (not categorical)
YES. Although some technical variants exist for categorical factor analysis, the standard PCA/Factor is only prepared to process metric scale variables.
In a good factor analysis, we expect to get as many factors as possible
FALSE. A main goal of factor analysis is dimensionality reduction so, the less the number of factors (without a great loss of information) the better.
When there exists an underlying factor, being unique and common, we will get a high eigenvalue for the first factor
TRUE. A high value means a factor accounting for a high proportion of variance.
VARIMAX, QUARTIMAX and EQUAMAX are orthogonal rotations.
TRUE. You can find it in the class document. All of them keep orthogonality of initial factors after rotation.
The proportion of variance accounted for by each factor / component equals its eigenvalue divided by the number of variables
TRUE. The eigenvalue is the variance=information of each factor. Given that variables are z-scores, the total amount of variance is equal to “N=number of variables”. Dividing the Factor eigenvalue (variance of the factor) by “N” we get the proportion of variance captured by this factor.
Using PCA as factor extraction, we will sometimes get oblique factors solutions
FALSE. PCA implies orthogonality between factors.
A low communality for a given input variable may suggest that we can remove that variable from the factor analysis
TRUE. A low communality implies that the variable does not share common factors with others.
Factor analysis can de used to get a metric measurement of an unobservable feature
TRUE. If we are able to measure some variables that are somehow related to an underlying unobservable feature, FACTOR analysis can extract a metric representation (measurement) of that unobservable feature
Standardized versions of input variables will give all the input variables the same importance / weight in our factor analysis.
TRUE. Otherwise, we take a risk of weighting some variables more than others (although this is not the case for PCA, could be a risk when using other extraction methods)
We could use a FACTOR analysis to test if different items in a questionnaire are linked with the same latent/underlying concept
TRUE. As mentioned in class, FACTOR analysis could be used to test consistency of a set of items in a list. Those exhibiting low communality with others are supposed to be un-connected with the common underlying factor.