Research online, buy online
Research online, buy offline
Research offline, buy online
Research offline, buy offline
I had always predicted that research offline, buy online would be the model for the future - people like to kick the tires, but hate dealing with salespeople, or to have to carry heavy goods home (online also usually gives a lower price), but it seems by some distance that research online, buy offline is the model that works best, i.e. find the best buy and go to the store.
This is a direct problem for internet TV advertising, where proving that your ads are building a brand is a much more difficult argument than measuring actually off ad sales. For all its power, have you ever heard anyone say 'I bought this 'cause I liked the TV ad..'