Round cat is right on.
So are you for asking. This is def. the way to go.
How I would define narrowing someones range?
If you pick up JJ in the Hi-jack and make a standard raise. The btn calls. You can immediately start narrowing his range. He doesnt have QQ+, AK. Probably not even AQ.
So basically your 1 step closer to knowing his cards. However, there are many steps. Taking into consideration all of the other reads you have on him, you can get pretty accurate. But it gets REALLY hard with other variables as well. Unknowns/ Aggros/ Dry boards/ draw heavy brds. The list goes on forever.