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Finding the Pearson Correlation


Published: 15 Feb 2017
Last Modified Date: 06 Apr 2017

Question

How to find the Pearson correlation of two measures in Tableau Desktop.

Environment

Tableau Desktop
 

Answer

Please note that New correlation and covariance functions were added to Tableau Desktop 10.2, for more information see What's new in Tableau Desktop.

Step 1: Create a scatterplot

This example uses Superstore sample data. 
  1. Drag Profit to Columns and Sales to Rows.
  2. Drag Customer Name to Detail.
  3. In the Analysis menu, uncheck Aggregate Measures
  4. Right-click the view and choose Trend Lines > Show Trend Lines.
  5. Right-click the view again and select Trend Lines > Describe Trend Model

Step 2: Calculate the correlation

Locate the R-Squared value in the Describe Trend Model dialog box. In this example, the R-Squared value is 0.229503.
User-added image
Using a calculator or other program, calculate the square root of the R-squared value. This is your correlation (r). Rounded to two digits, the value in this example is 0.48. 
 

Additional Information

A correlation, r, is a single number that represents the degree of relationship between two measures. The correlation coefficient is a value such that -1 <= r <= 1.

A positive correlation indicates a relationship between x and y measures such that as values of x increase, values of y also increase.

A negative correlation indicates the opposite—as values of x increase, values of y decrease.

The closer the correlation, r, is to -1 or 1, the stronger the relationship between x and y.

If r is close to or equal to 0, there is a weak relationship or no relationship between the measures.

As a general rule, you can interpret r values this way:

  • +.70 or higher indicates a very strong positive relationship
  • +.40 to +.69 indicates a strong positive relationship
  • +.20 to +.39 indicates a moderate positive relationship
  • -.19 to +.19 indicates no or a weak relationship
  • -.20 to -.39 indicates a moderate negative relationship
  • -.40 to -.69 indicates a strong negative relationship
  • -.70 or lower indicates a very strong negative relationship
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