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Experiment…read more

Slide 2

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Designing an Experiment
Independent variable: What is being changed each time so you manipulate one variable each time
Dependant variable: What is being measured
Repeated Measures: test each individual in both conditions and then compare performance on both
condition one condition two
Independent group: test one group in one condition and different group of people in the second
condition and then compare
condition one condition two
Matched pairs design: participants are paired up by matching them on key variables…read more

Slide 3

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Designing an Experiment
Operationalisation: we specify how we will measure the
Hypothesis: one tailed hypothesis e.g. "people who listen
to music while studying perform less well on a memory
test that people who work in without music"
Two tailed hypothesis: people who listen t music while
studying perform different on a memory test than
people who work without music. (direction is not given)
Null hypothesis: when you predict there is no difference or
relationship…read more

Slide 4

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Extraneous variables
Participant Variables Situational variables
Age intelligence motivation and experience: Time of day, temperature and noise:
In an independent groups design Variable effects the performance e.g
participants in one group may be more participants would do better on a exam in
intelligent than the other groups . E.g. the morning rather than in though day time
people who hardly listen to music compared Investigator/experimenter bias
to people who listen to music. Investigator bias occurs when there is an
Gender: effect in the investigators expectations on
Women and men differ in behaviours. If participants behaviour. E.g. experimenter
there are more women in one conditions more encouraging on a task that makes the
might mask affects of the independent participants perform well.
variable Demand characteristics:
Controlling participant variables: Participants change their behaviour so it
Using repeated measures design can looks" suitable" for it purpose . It usually
control participant variables changes the reliability and validity.
Or could use a matched pairs design Controlling situational variables:
Using an independent measures design
Keeping variable effects constant/…read more

Slide 5

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Types of Experiment
Laboratory experiment:
Controlled conditions with an artificial set up
· Can establish cause and effect
· Well controlled , minimising extraneous variables. This shows that the IV did cause DV.
· Artificial situation lacking realism- low ecological validity. Ecological validity is how much it relates to real life
· Generalisability, e.g. Sample bias
Field experiment-
An experiment conducted in participants natural environment which mean they are more likely to behave as they do
ordinarily .
· Iv manipulated and therefore cause and affect is clearly shown
· More natural environment- less aware of being studied- increases ecological validity
· Less control over extraneous variables
· Problems in sampling
Natural/Quasi Experiment
Experimenter does not manipulate the iv but takes advantage of the naturally occurring ic
· Can study real life problems so increases ecological validity
· No link between cause and effect
· Participants aware of being studies, reducing naturalness…read more

Slide 6

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Reliability and Validity
Relaibilty would be concerened with
consistency, and agian if it is repeated or tried
by two are more people prodcuing similar
resutls and finding, it is mor realible (inter
rater reliabilty)…read more


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