I have never once bought a product because of an ad, unless the ad was telling me about something I didn't know existed. Perhaps others are weak-minded enough to do so, but not everyone is.
How do you know? The point of most ads isn't just to get you to make an immediate purchase but to make that brand part of your active memory so you will be more predisposed to choose it when you see it available. There are some ads that don't even mention any specific product at all.
