What is the effect of recruiting volunteers to participate in a ...

[bio_gurl]

What is the effect of recruiting volunteers to participate in a randomized experiment?
 a. The results will be more credible because people who really wanted to participate took part in the study.
  b. The results cannot necessarily be extended to the larger population.
  c. There will be no effect because the people are always randomly assigned to treatments, eliminating any type of bias.
  d. Researchers are never allowed to use volunteers to participate in an experiment.

Question 2

Which of the following is a property of a confounding variable?
 a. It is related to the explanatory variable; individuals who differ on the explanatory variable are also likely to differ on the confounding variable.
  b. It affects the response variable.
  c. Its effect on the response variable cannot be separated from the effect of the explanatory variable on the response variable.
  d. All of the above

[wshriver]

Answer to Question 1

B

Answer to Question 2

D

[bio_gurl]

Gracias!

[sailorcrescent]

Thanks for the timely response, appreciate it