A consultant who specializes in political campaigns tests the success of three ads in convincing registered voters to support a candidate. He wants to test two groups of registered voters - those who currently express weak or strong affinity to the registered party. The ads run for 30 seconds and feature issues of the campaign. One ad presents the candidate's rationale for supporting issues, a second ad berates the opponent of the candidate and encourages people to vote for the candidate, and the third ad contrasts the two candidates' positions on issues. What is one of the factors mentioned in this scenario? How many levels does it have and what are they? Is it Between Subjects design or Within Subjects design