The Spearman Correlation (Jump to: Lecture | Video )

In the last lectures I talked about Pearson’s r, which measures the relationship between two continuous (interval or ratio scale) variables.

Below is an example of some data that is related in a non-linear fashion. For this, we would use the Spearman correlation:

Figure 1.

Let's calculate the Spearman correlation for the following data set:

Figure 2.

To calculate the Spearman correlation, we must first rank the scores:

Figure 3.

We then calculate the correlation using these new ranks:

Figure 4.

We find an r of -1.00, meaning that our data has a negative relationship. As x increases, y decreases. As x decreases, y increases.