FINAL: Chapter 11 Threats to Internal Validity Flashcards
Why are we most concerned with internal validity in experiments?
Internal validity studies the ability to rule out alternative explanations for a causal relationship b/w 2 variables
What are the different threats to internal validity?
Maturation, History, Regression, Differential attrition, Testing, Instrumentation
What is a maturation threat?
Occurs when an observed change in an experimental group could have emerged somewhat spontaneously over time
What is a history threat?
Occurs when it is unclear whether the change in the treatment group is caused by the treatment itself or by an external or historical factor that affects most members of a treatment group around the same time of treatment itself?
What is a regression threat?
When a group average is unusually extreme at time 1, then next time the group is measured the mean in likely to be closer to the typical value
What is differential attrition threat?
Occurs when a certain kind of participant drops out of a study before it ends (serious threat when subject that dropped has extreme scores at pretest)
What is an instrumentation threat?
When the thing doing the measurement changes over time
What is a testing threat?
Specific type of order effect when changes in the participant score on the posttest are a result of taking a test more than once
What is the placebo effect?
Positive outcomes observed after treatment is administered that cannot be attributed to the properties of the treatment itself (to prevent, use a double-blind study)
