Know when it is hard for the Leap to see a hand. When near the edge of the screen or when one hand is occluding another, confidence will drop from one to zero.
Use this within your app to filter out suspect data, especially for actions which cannot be undone.
Notice subtleties - such as when the hand is far forwards and low, it can be obscured by the wrist.
The motion data for this example was recorded with the LeapJS Recorder: developer.leapmotion.com/recorder