Research Methods : Experimental Design Flashcards
What is experimental design ?
The different ways in which the testing of participants can be organised in relation to the experimental conditions
Independent groups design
Participants are allocated to different groups where each group represents one experimental condition
Repeated measures design
All participants take part in all conditions of the experiment
Matched pairs design
Pairs of participants are first matched on some variables that may affect dependent Variable. One member of the pair assigned to condition A and the other to condition B
Random allocation
An attempt to control for participants variables in an independent groups design which ensures each participant has the same chance of being in one condition than other
Order affects
A confounding variable that occurs in repeated measures designs arising from the order in which conditions are presented eg boredom effect
Counter balancing
An attempt to control for the effects of order effects in a repeated measures design : half of the participants experience the conditions in one order (a then b) and the other half in the opposite order (b and a)
Independent group design details
Different participants used in each condition
Allocation of participants should be by random allocation
Participants will take part in both levels of IV
Strengths of independent groups design
Order of effects are avoided as participants only take part in one condition so they cannot get better or worse between conditions they cannot get tired or bored.
Demand characteristics are avoided participants only take part in one conditions so they are less likely to guess the aim and alter their behaviour
Limitations of independent groups design
Participants variables - a different between the groups might be because of the characteristics of the group rather than the manipulation of the DV.
More participants are required to produce the same amount of data as Repeated measures design
Details of repeated measures design
Same participants take part in both in both conditions of the experiment
Each condition includes the same group of participants
Strengths of repeated measures of design
Participants variables are controlled. There are no individual differences between the groups as the same people are taking part.
Fewer participants are required - all participants are taking part in all conditions
Limitations repeated measures
Demand characteristics- participants more likely to work out the aim of the study as they are taking part in both aims.
Order effects-the order of effects may have improved between condition. Some people declined.
Why is counter balancing used?
It balances out so minimising the order of effects as they are going both way
Matched pairs design details
Pairs of participants are matched in terms of key variables such as age then one member is then placed in the two different conditions
