M7: Controlling Threats to Internal Validity

Question 1

What are ways to control threats to
internal validity?

Answer 1

• Randomization
• Placebos, Blind & Double-blind studies
• Standardize experiments & instruments

Question 2

What is the purpose of Placebos, Blind and Double-blind studies?

Answer 2

Helps reduce experimenter bias/participant expectancies

Question 3

How can Randomization control
internal validity?

Answer 3

• Random assignment – controls for history
• Matched pairs – e.g., age, gender
• Randomizing treatments or counterbalancing
• ABC v. ACB v. BAC v. BCA v. CAB v. CBA

Question 4

How can we Standardize experiments and instruments as much as possible?

Answer 4

E.g., Script every researcher uses, everything in the same order, make sure instruments are calibrated after every test