The study compared two types of correlation coefficients for traits of Pinus sylvestris L. The researchers looked at Pearson's coefficient, which measures a linear relationship, and Spearman's coefficient, which looks at a monotonic relationship. They found that the two types of coefficients showed consistent results in terms of direction and strength. When there was a difference in the correlation direction, the coefficients were not statistically significant. Using medians for estimation was found to be robust to outlier observations.