Categorical Principal Components Analysis Bootstrap

The Bootstrap dialog specifies parameters for bootstrap analysis.

Perform bootstrapping. Performs bootstrap resampling.

  • If plots of loadings, categories, or component scores are requested, extra plots are displayed. These plots display the points for the data sample and the bootstrap estimates. Transformation plots include confidence regions. A plot for the eigenvalues is also displayed.
  • If a two-dimensional solution is specified, confidence ellipse plots for the eigenvalues, the component loadings, the category points, and the object points are displayed.
  • Bootstrap resampling is not available if you specify a rotation method in the Options dialog.

You can select Balanced or Unbalanced bootstrapping.

Number of samples. The number of bootstrap samples that are used to calculate the bootstrap estimates. The value must be a positive integer.

Confidence level. The confidence level of the bootstrap estimates, expressed as a percentage. The value must a be a positive number less than 100.

Matching Method. The two alternatives are Procrustes and Reflection.

Confidence Ellipses. Controls the threshold area for confidence ellipses in plots. For areas greater than (> operator) the specified value, the number of ellipses decreases as the threshold value increases.

  • The settings in this group are only available if the number of dimensions that are specified on the main dialog is 2.
  • Confidence ellipses for loading plots are available only if Display component loadings is selected in the Loading Plots dialog.
  • Confidence ellipses for object plots are available only if Object points is selected in the Object and Variable Plots dialog.
  • Confidence ellipses for category plots are available only if one or more variables are specified in the Category Plots list in the Category Plots dialog.

Number of ellipse contour points. The number of plot points used to draw each confidence ellipse. Larger values produce smoother ellipses. The value must be a positive integer less than or equal to 100.