3) Experimental designs key terms Flashcards
What is meant by experimental designs?
Refers to how participants are organised across the conditions
What is experimental designs often confused with?
Experimental method
What is an independent groups design?
Each participant takes part in one condition only / they are only selected for one group
How are participants randomly allocated?
“The lottery method”
“The random number generator method”
What is the lottery method?
-obtain a list of everyone in the population
-put all the names into a hat
-select the number of names required
What is the random number generator method?
-number every member of the population
-use a computer to pick a random number
-allocate one participant group “A” and the next group “B”
-alternate groups per person
-continue until everyone has been allocated to a group
What is a repeated measures design?
Each participant takes part in both conditions / they are selected for both groups
What is a matched pairs design?
Each participant takes part in one condition only, but participants are matched on variables considered relevant (age, IQ, gender)
How is a matched pairs design done?
Each individual is matched on a factor at an individual level to make it an equal and just experiment
What are the pros of independent groups design?
- order of effects are reduced as participants only take part in one condition
-they do not get to practice the task or become fatigued (fatigued effect)
-demand characteristics are reduced as participants take part in one condition; are less likely to guess the aim of the study
What are the cons of independent groups design?
-there are participant extraneous variables between the groups; lowering the internal validity of the study
-less economical than repeated measures as you need twice the amount of participants
(Random allocation is used to try to combat the problem of participant extraneous variables)
What are the pros of repeated measure design?
-participant’s extraneous variables are controlled
-more economical as there are less participants required
What are the cons of repeated measures design?
-order of effects / practice effects / fatigue effects
-demand characteristics
-> ABBA technique is used to counterbalance the order of effects
What are pros of matched pairs designs?
-participants only take part in one single condition
-order of effects reduced
-demand characteristics are less of a problem
-participant EV’s are reduced
What are the cons of matched pairs design?
-decrease in participant variables
-participants cannot be truly matched
-time consuming
-less economical
