Final Exam Review Flashcards
Independent group designs
AKA?
What are they?
How are groups arranged?
- Aka between subjects
- Compare differences between groups while controlling for differences within groups
- separate groups for each level of IV
Experimental methods
Establish causation if random assignment is used
An experiment is used to infer causality by using?
Manipulation of the IV
Control requires balanced samples. What does this mean and why is random assignment a good way to achieve this?
Controls for individual differences within groups providing for greater internal validity
Why is one group pre test post test design not an experiment?
No control
What is required to make a casual inference? Why does an experiment make this possible?
Covariation, time order relationship between IV and DV, elimination of alternative explanations
What does co variation mean?
The IV and DV are correlated; both events occurred around the same time
Time order relationship
IV changes, then DV changes
Internal validity
What is it?
Requirements?
Extent to which you can make a casual inference
Only occurs when all 3 aspects are met
External validity
Does intervention work in the real world?
Threats to internal validity;
Confounds
Extraneous variables
Systematic differences between groups
What are intact groups and why are they a problem?
Using pre existing groups
Results may have alternative explanation
Attrition
Loss of participants in a study
Mechanical loss
Factors external to participants
Not a big deal if infrequent
Selective subject loss
What is it?
How to control for it? (2 ways)
Internal factors
Can destroy comparable groups
Pretesting, drop one as another drops out
Participant and experimenter biases
Unethical manipulation of any part of an experiment that will aid in obtaining desired results
Double blind design
What is it?
Can control what?
Neither experimenter or participants know if they are in the control group or the treatment group
Can control experimenter effects
What is an independent groups design?
Between groups design
Separate group of participants for each level of the IV
What are between groups and within groups differences?
Q
Why can’t random assignment always be used?
Pre existing variables such as quasi experiments
Why can’t matched and natural groups designs not use random assignment?
No control because manipulation is not technically possible with pre disposed variables
3 types of independent groups?
Random
Natural
Matched
Random independent groups
Balance out individual differences
Randomly assign participants to level of IV
Natural independent groups
What is it?
True experiment?
Why or why not?
Naturally occurring IVs
Not true experiment (correlational because the already existing IV cannot technically be manipulated)
Matched independent groups
What is it?
When to use?
Instead of random assignment, groups formed on relative dimension
Works best w Smaller sample sizes
Repeated measures design
What is it?
How does it differ from an IGD?
Each participant completes all conditions of the experiment; participants serve as their own controls
Compares within group effects rather than between group effects
What are practice effects?
Change in participant’s responses over time due to learning a new task
Boredom, fatigue
What are anticipation effects?
Q
Purpose of counterbalancing?
To correct for
Advantages of the RMD
Participants are own controls, so less subjects are needed
Disadvantages of the RMD
Practice effects are possible if not properly counter balanced
Types of counterbalancing: complete
Block randomization
ABBA
Types of counterbalancing: incomplete
All possible orders
Latin square
Random starting order with rotation
Block randomization
What is it?
Size of blocks =?
Requires what?
Counterbalancing in which each block contains all conditions in random order
Size of block = number of cond
Requires many presentations to balance