In my analysis I determine the intergenerational transmission of social status. In the literature it is common to use OLS regressions for this purpose. In addition to these regressions, I also calculate the Spearman rank correlation coefficient for two generations, because it does not assume that the correlation is linear.
But now I would like to include the grandparental generation as well. Can the Spearman correlation coefficient be extended in such a way that I can also include this third variable in the analysis?