How to measure introveraion and extroveraion?

Which of these are more important when determining if someone is an extrovert or an introvert; the actions they've took or the way they behave daily around people ? And if someone likes to spend time at their computer but other than that they show all possible extroversion traits such as being loud, assertive, talkative, enthusiastic, energetic, interrupts speech, uses lot of hand gestures, and overall is a very active and extroverted person but just prefers not to go out, does that make that person an introvert? In other words they behave like an extrovert in everything they do, but they prefer to spend time at home, could they call themselves an introvert? Please help out, thanks.

Edit: The title's supposed to be introversion and extroversion, i mistyped