What is the major purpose of controls in research?
A) to produce research hypotheses when combined with problem statements
B) to generate initial ideas
C) to counteract threats to validity
D) to increase participants' willingness to be involved
Question 2
Which of the following is NOT one of the four types of commonly used controls mentioned in the text?
A) control over subject and experimenter effects
B) control achieved through selection and assignment of participants
C) control over population selection and specific observational procedures
D) control achieved through specific experimental design