This article describes how to create a correlation matrix which visualizes the correlations between variables as a heat map.
A data set containing two or more variables which have a Structure set as Numeric or Numeric- Multi. Note that binary categorical variables can also be used as inputs but will be converted to numeric when calculating the correlation coefficients.
1. Select Anything > Advanced Analysis > Correlation > Correlation Matrix or select Home > Anything > Advanced Analysis > Correlation > Correlation Matrix.
2. Select your inputs from the object inspector on the right using one of the following methods:
- With Data source set to 'Variables' (this is the default setting) or 'Variable sets' , select two or more variables from the Variables drop-down box.
- Change Data source to 'Table' and then select your table from the Table drop-down box. Rows and columns that you don't want to include in the analysis can be specified by entering these in the Ignore box.
3. Choose the Correlation Type:
- Pearson (default) - based on the actual data
- Spearman - based on the ranks of the data (this is less susceptible to outliers and thus less likely to represent the true nature of the correlation).
4. Click the Calculate button (or tick the Automatic checkbox at the top of the object inspector) to generate the correlation matrix.