Research Methods (Psychology AS)

Research methods, Hypotheses, Experimental Designs, Reliability, Validity, Ethical Issues, Sampling, Data Analysis

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  • Created on: 04-05-11 13:09
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Research Methods
Research Method Strengths Limitations
Laboratory experiment ­ artificial environment, High control of variables Demand characteristics ­ people may
the experimenter manipulates the IV and the DV Able to choose representative sample change behaviour as they are aware of the
Often cheaper and less time consuming experiment
than other methods Low ecological validity ­ artificial
experiment
Field experiment ­ real environment, the Natural behaviour as people are unaware Little control of extraneous variables
experimenter manipulates the IV and measures the of experiment Can lead to ethical issues ­ informed
DV High ecological validity ­ `real' consent
environment Can be timeconsuming and costly
Natural experiment ­ real environment, the IV Can be used in situations where it would IV not controlled by experimenter
changes naturally and the experimenter measures be unethical to manipulate the IV Little control of extraneous variables
the DV Natural behaviour as people are unaware No control over allocation of participants
of experiment ­ may have low sample validity
Observational study ­ real environment, there Natural behaviour as people unaware of No control of any variables
are no changes experiment Can lead to ethical issues ­ informed
consent
Demand characteristics ­ people may
change behaviour as they are aware they
are being observed
Interview Rich data ­ interviewer able to follow up Social desirability bias people say what
each answer they think looks good
Time consuming and expensive

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Effect of interviewer ­ participants'
answers may reflect relationship with
interviewer
Questionnaire Many people can be questioned quickly ­ Social desirability bias ­ people say what
generates lots of data they think looks good
Easy as interviewer does not have to be People may lie, especially with
present sensitive/personal issues
Difficult to phrase questions clearly ­ may
obtain different interpretations of questions
Case study Rich in depth data Difficult to generalise from individual cases
Can be used to investigate instances of as each has unique…read more

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Investigations
Hypothesis
A hypothesis states the expected relationship between an independent variable and a dependant variable e.g. doing homework with or without music (IV)
and the results of the homework (DV). It is always written in the future tense.
Directional hypothesis ­ states the expected direction of your results e.g. participants who do homework without music will produce better results than
participants who do homework with music.
Nondirectional hypothesis ­ predicts that there will be a difference between the conditions e.g.…read more

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Repeated measures design ­ one group in Eliminates individual differences Order effects participants may become
both conditions. E.g. a group does a memory test Fewer people are needed than with bored or guess what experiment is about
in the morning and then a similar (but not the independent groups design. after first time and therefore change
same) memory test in the afternoon behaviour
Matched pairs design ­ participants matched Reduces individual differences Time consuming and difficult to find
on key variables. E.g.…read more

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Ecological validity ­ the extent to which the task can be applied to the world outside the research situation
Sample validity ­ the extent to which the participants represent people outside the research situation
Temporal (time) validity ­ the extent to which the findings can be applied to any era
Internal validity ­ the extent to which the experiment measures what it is set out to measure
Ethical issues
Ethical issue Dealing with ethical issue
Informed consent ­ participants should have given their formal agreement…read more

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Sampling
Sampling technique Strengths Weaknesses
Opportunity sample ­ a sample of participants Less time consuming first participants Biased sample is drawn from small part
produced by selecting people who are most easily you can find are used of target population. E.g.…read more

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Range ­ the difference between the highest and Easy to calculate Can be easily distorted by extreme scores
lowest scores
Standard deviation ­ measure of dispersion that Takes account of all scores More difficult to calculate compared to
indicates the spread of data around a central Sensitive measure of dispersion the range
value
Measures of central tendency
Measure of central tendency Strengths Weaknesses
Mean ­ the average value calculated by adding It makes use of all the values in the data Misrepresentative of the data…read more

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