I/E, J/P, T/F are often fairly apparent after you meet someone a few times
but I've known people for years I can't tell if they're N or S
being handy is one indicator, but not always apparent from typical office/party/playing sports activities
many Ns, like me, don't walk around discussing theories, and some people who seem like Ss do, so that doesn't really seem to work
not enough evidence in daily life for me, how do you tell?