Threats to Internal Validity

Question 1

Internal Validity

Answer 1

the extent to which you’re able to say that no other variables apart from the IV caused a change to the dependent variable

Question 2

External Validity

Answer 2

the ability of a researcher to generalize the research findings to a different situation or population

Question 3

8 classic threats

Answer 3

All diminish or eliminate internal validity

Question 4

History

Answer 4

An event(s) that occurs outside the context of the research study; occurs b/w the initiation of the study or initial measurement and the measurement of the outcome. The event is also related to the DV

Question 5

Testing

Answer 5

taking a measurement/assessment affects subsequent measurement/assessment (usually with the same instrument). This is especially problematic for repeated measures designs

Question 6

Maturation

Answer 6

broadly indicates internal changes in participants that occur over time. Changes can be age related, but also include factors such as boredom or changes in knowledge

Question 7

Attrition/Mortality

Answer 7

the loss of participants over the course of the study. This may result from subgroup differences. Especially problematic when there is a large difference in attrition b/w study groups

Question 8

Regression to the mean/statistical regression

Answer 8

the effect of selecting participants based on extreme scores, characteristics, or behaviors. Over time, participants may become “more average” due to factors not related to the study

Question 9

Instrumentation

Answer 9

Changes in instrumentation (scales/tests), faulty equipment, or changes in scores (judges or criteria) that affect the results

Question 10

Selection

Answer 10

the effect of having non-equivalent groups or unaccounted for initial group differences at the beginning of the study

Question 11

Selection/social interaction

Answer 11

Participants from different groups may compare notes and either figure out the aim of the study or feel resentful of others.