Intuitive SIA = consider yourself a random sample out of all possible people
SSA = consider yourself a random sample from people in each given universe separately
e.g. if there are ten people and half might be you in one universe, and one person who might be you in another,
SIA: a greater proportion of those who might be you are in the first
SSA: a greater proportion of the people in the second might be you
Intuitive SIA = consider yourself a random sample out of all possible people
SSA = consider yourself a random sample from people in each given universe separately
e.g. if there are ten people and half might be you in one universe, and one person who might be you in another, SIA: a greater proportion of those who might be you are in the first SSA: a greater proportion of the people in the second might be you