Which of the control techniques has the most power to insure that unidentified, extraneous variables do not have differential effects on the different groups in the experiment?

Which of the following is a public environmental interest group?

A. National Mining Association B. American Gas Association C. Sierra Club D. American Farm Bureau Federation E. National Association of Water Companies

Which of the following represents a rationalist's explanation for not voting in a local election?

A. The person running for office is not appealing. B. Getting to the polls is the duty of being a citizen. C. One person's vote isn't going to be that critical in deciding the outcome. D. There isn't really a difference in candidates.