I would like to test whether the general relationship between the number of years of education and the wage is linear, exponential, etc. Or in other words, does going from 1 year to 2 years of education have the same impact on wages as going from 10 to 11. I want a general assessment for the world and not for a specific country.
I got standardized data from surveys on several countries and multiple times (since 2000). My idea is to build a multilevel mixed-effects model, with a fixed effect for the number of years of education and random effects for the country, the year of the survey and other covariates (age, sex, etc.). I’m not so used to this type of model: do you think it makes sense? Is this the most appropriate specification of the model for my needs?