Spearman's rho correlation

The Spearman correlation measures the degree to which two variables have a one-direction relationship (Gravetter and Wallnau, 2013). The Spearman correlation is used when the data is ordinal (in ranks) or when you want to measure the consistency of the relationship (how linear is the relationship between two variables). This type of correlation actually uses the same formulas as the Pearson correlation; the difference is that Spearman uses ranked or ordinal data, and Pearson uses the actual data values.

To use this equation, simply plug in your data, and the rest is done for you.

References

Gravetter, F. J., & Wallnau, L. B. (2013). Statistics for the Behavioral Sciences. Wadsworth, CA: Cengage Learning.