Advertisers put a ton of time and money into evaluating the effectiveness of their prospective campaigns, and they're always looking for new ways to find the most effective message. To that end, some researchers have just published a study in which they used Google's AdWords program as an inexpensive way of testing different "persuasive messages." Simply posting a few Google AdWords ads with variations on a different advertising message lets users quickly gather data on which message is more persuasive to a wide audience. The benefits of this program (over more traditional methods like focus groups or surveys) are that the subjects don't realize that they're part of an advertising test, they're just responding to an ad posted online as they would for any other advertisement — the respondents also don't need to be paid directly (unlike Amazon's Mechanical Turk program, and the cost for placing Google AdWords is relatively minimal compared to other methods.