I will be blunt: this is an old exam question of a course that covers Molecular Dynamics (MD) and Monte Carlo (MC) simulations.
Explain how to determine the severity of finite-size effects.
My idea: Since we are talking about MD and MC, finite-size effects are related to the fact that we can only simulate systems of finite sizes. Contrarily, in nature systems usually approach very large sizes, i.e. they are in the thermodynamic limit.
I found these lecture slides which gives me some ideas, but I am not sure that this is what is being asked in the question above.
Any thoughts, and pointers to slides / scripts are very welcome.