I have started to work with regression models for angular data. In particular with the package
I checked previously in this forum if there was something analogous to Pearson R-squared for angles. As it was not completely clear I read the literature about the topic from Sarma and Rao Jammalamadaka (1993) (p. 119, Eq 3.6). Finally I got the book 'Circular statistics in R' in which they confirm (Ch 8.6, p. 169) that the output
rho of the function
circ.reg, is a measure of the fit analogous to Pearson R-squared, also with values between 0 and 1.
So far so good but when trying to understand the formulas I do not see how this value can be related to the residuals or the variance in the model. Can someone explain?