Table of Contents

Introduction

Tool Use

CADStat: Statistical Tools for Causal Analysis

Factor Analysis/Principle Components Analysis

Introduction

Factor analysis and principle components analysis provide a multivariate approaches for examining how groups of variables are correlated.

Tool Use

Select Analysis Tools -> Factor Analysis from the menus. A dialog box will open. Select the data set of interest from the pull-down menu, or browse for a tab-delimited text file (the example provided uses envdata.or.txt, found in CADStat/extdata). The Data Subsetting tab can be used to select a subset of the data file by choosing a variable from the pull down menu and then selecting the levels of that variable to include. You can hold down the <CTRL> key to add several different levels.

Select the No. of Factors you with to compute. Select 0 to compute a principle component analysis. Select one or more factors to compute a Factor Analysis.

Select all Variables that you wish to include in the analysis. You may hold down the <CTRL> key to several variables.

Further options are avalable depending on whether a principle components analysis or factor analysis is selected.

  1. Principle Components Analysis

    • Scree Plot: Output a scree plot of eigenvalues, showing the variance associated with each component. The sum of these variances is equivalent to the total variance in the selected variables.
    • Loading/Score Plot: Output a biplot of the first two principle components.
    • Rotated Variables: Return the rotated variables, appended to the original data frame.
  2. Factor Analysis

    • Varimax/Promax: Select the rotation you with to apply to your factors
    • None/Thompson/Bartlett: Select the type of scores that you would like returned. See R-help pages on factanal for more information. Scores will be returned appended to the original data frame.
Screenshot of Factor Analysis dialog page. 'envdata.txt' has been loaded as the Active Dataset.