During a practice swing the ball is dislodged from tee is it counted as a stroke?

This came from Brent Kelly of About.com:Golf. I hope this answers your question. "If the ball is on the teeing ground and you have not yet made a stroke at the ball, then the ball is not yet in play. And accidentally hitting the ball with a practice swing in that situation does not result in a stroke or a penalty. However, once you've made a stroke at the ball on the teeing ground, the ball is considered in play until you hole out. Then the question of whether a practice swing that makes contact is a stroke or penalty (or both) is covered under Rule 18, "Ball at Rest Moved." And here's the ruling: If you accidentally move a ball in play with a practice swing, it's a one-stroke penalty. You must replace the ball to its original position and play it correctly. Failing to replay the ball from its original position results in a total penalty of two strokes in stroke play or loss of hole in match play."