Experimental Design Flashcards
Experimental design
The different ways in which participants can organise in relation to the conditions in an experiment
Independent groups
Participants are allocated to different groups where each group represents one experimental condition
Control group
A group of participants who receive no ‘’treatment’. The behaviour act as a baseline against which the effect of the independent variable may be measured
Strength of independent groups
Order effects or not a problem
Order effect
In a repeated measures design, an extraneous variable arising from the order in which conditions are presented
Weakness of independent groups
The participant in each group may differ
Allocation to conditions
In an independent group design, each group receives one level of the IV
Repeated measures
When all participants take part in all the conditions of the experiment
Strength of repeated measures
The problem of participant variables is removed
Weakness of repeated measures
Order effect
Counterbalancing
Half of the participants complete conditions in one order, and the other half in the opposite order
Control condition
The condition in a repeated measures design that provide a baseline measure of behaviour without the experimental treatment
Matched pairs
I has all our matched in terms of variables relevant to the study such as age or IQ. One member of each pair takes part in condition A of the experiment and the other takes part in condition B
Strength of matched pairs
Deals with some of the problems of both independent groups and repeated measures
Weakness of matched pairs
Matching participants takes time and is never exact
Sample
A subset of the target population which aims to be representative of that population
Target population
The group that the researcher is interested in studying, from which a smaller sample is selected
Sampling method
The system used to produce a sample
Random sampling
Produced by using a random technique in which every member of the target population has an equal chance of being selected
Strength of random sampling
There is no bias
Weakness of random sampling
Takes more time and effort that other methods
Opportunity sampling
Produced by selecting people who are willing and available at the time
Strength of opportunity sampling
Relatively easy to do because you simply go to people who are nearby
Weakness of opportunity sampling
Likely to be unrepresentative of the population
