Threats to Internal Validity

Question 1

IV levels differ beyond the intended manipulation

Answer 1

Design Confounds

Question 2

Participants in one IV differ in a systematic way from participants in another IV

Answer 2

Selection Effect

Question 3

The order of events differs from one group to another

Answer 3

Order Effects

Question 4

Spontaneous changes in behavior occur over time, not due to the IV

Answer 4

Maturation Threat

Question 5

An outside event occurs to all the participants at the same time the IV is manipulated

Answer 5

History Threat

Question 6

Extreme scores become less extreme over time

Answer 6

Regression Threat

Question 7

Scores change over time just because the participants have taken the test more

Answer 7

Testing Threat

Question 8

Effect that occurs only because participants believe they are receiving a valid treatment

Answer 8

Placebo Effect Threat

Question 9

In a pre/post test study a threat occurs when a systematic type of participant drops out before the end of the study

Answer 9

Attrition Threat

Question 10

A measurement or instrument may change with time and repeated use because of the way the researcher operates it

Answer 10

Instrumentation Threat

Question 11

The expectations of the observer influences the DV (ratings or assessment)

Answer 11

Observational Bias

Question 12

Threat that occurs when participants takes cues from the observer and behave in ways consistent with the hypothesis

Answer 12

Demand Characteristics

Question 13

Causes of Null results:

Answer 13

1) IV doesn’t effect DV (hypothesis is wrong)
2) Type II Error (effects are not significant in the sample)
3) The difference between groups is too small
4) Too much within group variability