Perhaps a basic question but I would appreciate some explanation on this topic :)
I have a dataset covering approximately 30,000 loan applications. Besides characteristics of the loan (e.g., interest rate, loan duration, etc.) and borrower (e.g., age, educational level, etc.) it includes the year that the applicant applied for the loan as well as the applicant's country.
I want to investigate if gender has an influence on the interest rate of a loan. In deciding whether to use a fixed-effects model, I was wondering whether it would be possible to include both a country and a year fixed effect since my main variable of interest (gender) is time-invariant, and what could be the reasons for including fixed-effects in the first place?