If a human observer becomes more proficient in the course of a study, the type of threat to internal validity is called a change in

The "free-rider barrier to group membership" is the idea that individuals will not join interest groups unless they get something for free

Indicate whether this statement is true or false.

Assume that in the Democratic primary, Candidate A won 48 percent of the vote while Candidate B won 45 percent and Candidate C won 7 percent. What happens next? a. Candidate A and B, the top two vote-getters, will face each other in a runoff

b. Candidate A, the top vote-getter, officially wins the Democratic nomination due to winning more votes than the other candidates. c. Multiple, repeated elections will be conducted until a candidate receives a majority of the primary vote. d. Because none of the candidates received a majority of the vote, a new primary with different candidates will take place in the near future. e. None of these will happen.