How to Create a Correlation Matrix

This article describes how to create a correlation matrix that visualizes the correlations between variables as a heat map.

Requirements

Method 1: A data set containing two or more variables that have a Structure of 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. See Variable Sets for more info on how to set the measurement scale and values for analysis.
Method 2: A pre-calculated, aggregated table of correlation values (correlation matrix).

From the toolbar, select Table > Specialty Tables > Correlation Matrix.
Select your inputs from the object inspector using one of the following methods:
- With Data > Data source set to Variables (this is the default setting) or Variable Sets, select two or more Numeric or Numeric-Multi variables from the Variables dropdown box. This will run the correlation on the respondent-level values - for example the raw data for brand attitude across different brands:
- Change Data > Data source to Table and then select your table from the Table dropdown box. Rows and columns that you don't want to include in the analysis can be specified by entering them in the Ignore field. Using a table as the data source runs the correlations on the values shown in the table comparing the columns shown. You may want to do something like this if you want to see a metric over time -- for example brand attitude over time:
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).
Click the Calculate button (or tick the Calculate Automatically checkbox at the top of the object inspector) to generate the correlation matrix.

If the correlation matrix has already been calculated and needs to be imported into the Displayr document, then you can paste the table into your Displayr document.

A correlation matrix created using either Method 1 or Method 2 can then be used to create a heatmap.