One goal of formative campaign research is to create or select messages that have the greatest likelihood of influencing the target audience's beliefs, attitudes, or behaviors. Message designers assess the perceived effectiveness (PE) of messages prior to the campaign on the assumption that such measures are indicative of the impact these messages will have during the campaign. Roughly speaking, PE is an estimate of the degree to which the message will produce the intended change in the intended audience. It is frequently assessed using semantic differential scales such as persuasive/not persuasive, effective/ineffective, convincing/not convincing, and compelling/not compelling.

In ideal formative research, message effectiveness would be assessed by directly measuring changes in the attitude, belief, or behavior of the target audience. But, in reality, this is impractical. ...