<P> The polychoric correlation is another correlation applied to ordinal data that aims to estimate the correlation between theorised latent variables . </P> <P> One way to capture a more complete view of dependence structure is to consider a copula between them . </P> <P> The coefficient of determination generalizes the correlation coefficient for relationships beyond simple linear regression . </P> <P> The degree of dependence between variables X and Y does not depend on the scale on which the variables are expressed . That is, if we are analyzing the relationship between X and Y, most correlation measures are unaffected by transforming X to a + bX and Y to c + dY, where a, b, c, and d are constants (b and d being positive). This is true of some correlation statistics as well as their population analogues . Some correlation statistics, such as the rank correlation coefficient, are also invariant to monotone transformations of the marginal distributions of X and / or Y . </P>

When can we consider if a variable is dependent and independent