You should use a Spearman correlation, rather than a Pearson correlation, if:
A) Your data are measured on an interval scale.
B) Your data have no outliers.
C) Your data do not have a normal distribution.
D) You are not interested in statistical significance.

Question

Quizplus · Accepted Answer

Spearman correlation is a non-parametric test which doesn't assume a normal distribution in the data, unlike Pearson correlation. It is used when the data is measured on an ordinal scale or when it is not possible to meet the assumptions of normality and linearity required for Pearson correlation. Therefore, it is best to use Spearman correlation when the data does not have a normal distribution.

You Should Use a Spearman Correlation, Rather Than a Pearson