Experimental Methods 7.3

Question 1

What to experiments test?

Answer 1

Experiments test causal relationships
•Manipulate an independent variable (IV) and measure a dependent
variable (DV)
•Highly controlled situations and equivalent groups

Question 2

Variable

Answer 2

Characteristics that vary

- Variability based on the participants response

Question 3

Between group designs

Answer 3

• Ppts are exposed to only one level of the IV

* Helps reduce demand characteristics

Question 4

Subject variable between group design •Nonequivalent groups
•Limits causal inference
•Best practice is to try and match ppts on relevant variables

Question 5

Within group designs

Answer 5

• Participants are exposed to every level of the IV
• Ppts compared to themselves
• Stronger statistical power
• Can increase demand characteristics and “good participant” confounds
• Equivalent groups
• Counterbalance the order of the conditions

Question 6

Factorial designs

Answer 6

• Factorial designs: more than 1 factor (IV or subject variable)
• Fully within, fully between, mixed factorial designs
• Useful when predicting interactions

Question 7

True experiments

Answer 7

• Test causal relationships between an IV and a DV
• Internally valid
• It is the IV and not something else that led to the differences in the DV

Question 8

Quasi-experiments

Answer 8

•Causal conclusions about the effect of an IV or subject variable on a
DV cannot be made with a lot of confidence
•Incomplete control over the subject variable (or IV)

Question 9

Longitudinal designs

Answer 9

•Within group measurements are repeatedly taken over an extended
period of time•Special case where a subject variable can differ within a ppt

Question 10

Challenges of longitudinal studies

Answer 10

• Take many years

* Subject attrition

Question 11

Cross sectional designs

Answer 11

ex: •Measure people of different ages at the same time

Question 12

Cohort effcects

Answer 12

A cohort effect is a research result that occurs because of the characteristics of the cohort being studied. A cohort is any group that shares common historical or social experiences, like their year of birth.