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Experimental methods
Lab Experiment: Strengths: Weaknesses:
A highly controlled setting where High level of control Low ecological validity as
the IV is directly manipulated in High internal validity variables are being controlled
order to see its effect on the DV. Cause and effect can be inferred Increased demand
Field Experiment: Strengths: Weaknesses:
An experiment which takes place Higher ecological validity than a Less control over EVs
in a natural setting but the IV is lab experiment Lower reliability as it is difficult
still directly manipulated to see Reduces the possibility of to replicate exactly.
its effect on the DV. demand characteristics
Natural Experiment: Strengths: Weaknesses:
A researcher takes advantage of Very useful when it would be Lower reliability as it is difficult
a naturally occurring event to see unethical or not possible to to replicate exactly.
what effect it has on the DV. The manipulate the IV in a lab Low internal validity as it is not
IV is not directly manipulated it is High ecological validity possible to infer cause and
naturally occurring. effects as no variable are being
Correlational studies: Strengths: Weaknesses:
Studies which are carried out in Allows us to establish a Cannot measure cause and
order to identify a relationship relationship between two effect as it is not clear what is
between two variables. variables which would have been causing the relationship.
Correlations can be positive, different to test through artificial
negative or no correlation. experiments.…read more

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Observational Techniques
Controlled Observations: Strengths: Weaknesses:
A researcher conducts in a High level of control over EVs PPs often display socially
controlled environment. which increases the internal validity desirable behaviour as they
of the research know they are being watched.
Naturalistic Observations: Strengths: Weaknesses:
In a real environment where no High ecological validity No control over EVs
variables are manipulated. PPs tend to behave naturally as Informed consent cannot be
they do not know they are being gained from PPs
A statement about the purpose of
A precise, testable statement about
the investigation; what the
the outcome of the investigation.
researcher is trying do discover.
Directional ­ predicts a specific
Variables: outcome
IV ­ manipulated Non-Directional ­ says something
DV ­ measured will happen but is not clear as to
EV ­ anything except the IV which exactly what that something will be
might affect the DV Null ­ there will be no difference…read more

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Self-Report Techniques:
Questionnaires: Strengths: Weaknesses:
A set of questions used to collect Easy to collect a large amount of Low reliability and validity ­
data from a large sample of PPs. data in little time social desirability
Questions can be open or closed, Data can be easily analysed (if Open questions produced
giving qualitative or quantitative closed questions are asked) qualitative data which is tricky to
data respectively. analyse
Interviews: Strengths: Weaknesses:
PPs are asked a set of questions Structured ­ straight forward Structured ­ do not allow any
whilst sitting face to face with the and collect data easily deviation
researcher. The questions can be Unstructured ­ allow for a Unstructured ­ time consuming
structured or unstructured. deeper insight into the and expensive, proving difficult
interviewees viewpoint to analyse
Case Studies: Strengths: Weaknesses:
An in-depth study of an individual Provides rich data Difficult to replicate
or group of people High ecological validity Difficult to generalise due to the
Allows us to investigate areas situation and individual
which would be unethical to differences
explore if they were not naturally Possibility of researcher bias
occurring.…read more

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Experimental Design
Independent Groups: Strengths: Weaknesses:
PPs are randomly allocated to No order effects Individual differences are more
different conditions. Less demand characteristics likely to influence the results
More PPs needed
Repeated Measures: Strengths: Weaknesses:
The same PPs are in each Fewer individual differences Order effects likely
condition Less PPs needed Cannot use exactly the same set
of materials for both conditions
as PPs will realise and give the
same response
Matched Pairs: Strengths: Weaknesses:
PPs are matched on key variables No order effects Difficult to match PPs exactly
e.g. Gender, social backgrounds Reduces individual differences Matching can be time
etc consuming and expensive
Behavioural Categories ­ a specific set of behaviours that are defined before the start of the study. Behaviours should be
Pilot Studies ­ small scale studies designed to test out the proposed methodology of the main study.
Reliability ­ if you carry out the same study and get the same or similar results your study can be said to have high
Internal Validity ­ the controlling of all variables within your study to make sure it measures what it is designed to measure.
External Validity ­ the extent to which research findings can be generalised to other people.
Ethics ­ informed consent, protection from harm, deception, briefing and debriefing, right to withdraw, confidentiality,
anonymity.…read more

Slide 5

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Sampling Techniques
Random Sampling: Strengths: Weaknesses:
Every member of the target The sample is likely to be It is difficult to get a truly
population as an equal chance of representative of the people in random sample as you have to
being chosen the target population as you are make sure that everyone has an
not choosing people to take part equal chance of being chosen
Opportunity Sampling: Strengths: Weaknesses:
The same consists of people who Very quick and convenient as The sample will not be free from
are readily available to the the researcher can select the bias or representative of the
researcher people closest to them target population
Volunteer Sampling: Strengths: Weaknesses:
Participants apply to take part in Very useful for selecting specific A certain type of person is likely
the study PPs to volunteer so the sample will
not be representative…read more

Slide 6

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Demand Characteristics are cues in Analysis and Interpretation of Quantitative
the environment which help the PP work Data: Average ­ mean, median and mode
out what the research hypothesis is, Dispersion ­ range and standard deviation
leading them to behave in specific ways.
Analysing Qualitative Data:
Investigator Effects are subconscious
1. Collect data and write it up
characteristics or cues that the
investigator might display which may lead 2. Read and re-read your script
PPs to respond in desirable ways. 3. Identify several emergent themes
4. Reduce these themes into smaller groups of
Bar Graphs are used for nominal data. key themes in order to summarise the main
They have discontinuous data. points
Histograms are used for ordinal and
interval data. They have continuous data.
Scatter grams are used for showing the
relationship between two variables. They
tend to show a correlation.…read more


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