Which non parametric test instead of linear regression?
I have the measure (height) of bear dens from 1990 to 2020 (N=380). Each year a certain number of dens have been measured. All dens are different. I suspect that the size is decreasing over years, and of course I need to check it statistically. I though to use the simple linear regression analysis (X=years, Y=height), but the data don’t meet the assumptions needed (the Shapiro-Wilk test shows a significant deviation from normality). Which (non parametric) test would do you recommend in Jasp instead of the parametric regression test? Or which test to show if the size is declining over the years? I would be very grateful for any suggestion!
Thank you in advance