Psychology unit 1 spec A - Research Methods

I made a range of notes for my unit 1 exam in January, it really helped me ... hopefully it will help you too!

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  • Created on: 19-04-12 17:16
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Research Methods
A sample ­ A slice of the target population
Target Population ­ Known population that the test is specified too (eg. Children)
Validity ­ An experiment is valid if it measures what it is has been designed to measure (eg. Age and
effect on memory)
Internal Validity ­ Whether the IV has produced the change or the DV or an extraneous variable,
whether the researcher has tested what they intended to test. To gain high internal validity the
researcher has to control extraneous variables and ensure they are testing what they aimed to test.
Lab experiments have high internal validity.
External Validity ­ Generalising the results of a test to a whole population
Measuring Validity
Face Validity ­ Looking at a test and seeing if it looks as if it is measuring what it is suppose to
measure (eg. Questions related to aim)
Concurrent Validity ­ Comparing a current test with a previous one with the same aim to compare
results, similar results show constancy and therefore reliability.
Predictive Validity ­ Requires a test can make predictions about future results before it can be
considered valid.
Reliability ­ Results need to be reliable to be valid, results that are consistent are reliable, like a
test- retest to compare two sets of results. Open questions and unstructured interviews lack
reliability because they are hard to replicate.
Inter-Observer Reliability ­ Two or more researchers observing the same thing, they can interpret
the same information or behaviour differently, they must have 85% similarity to be considered
Random Sampling ­ Equal chance! An even variation from the target population; done either by
pulling names out of a hat or a random number generator. Can get freak sample (eg. Mostly boys).
Opportunity Sampling ­ Easy to find. A biased way because it is from a small section of the target
population. (eg. picking people from a college won't include older people)

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Volunteer Sampling ­ Placing an AD or notice to promote the experiment so participants come
forward willingly, again is a biased way of getting participants because they either have time on their
hands or a lot of free time, but they are more motivated and has less order effects on the test.
Types of sampling
Time Sampling ­ Observing within a specific time period. (eg. Recording an observation every 30
minutes) this minimises data to record.…read more

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Hypothesis of an experiment/test
Experiment Hypothesis ­ A testable statement, a prediction
Aim ­ What the researcher intends to investigate (purpose)
Directional Hypothesis ­ A specific difference; stating the outcome of the study, one way or the
other "Participants will..."
Non-Directional Hypothesis ­ Predicts a different but isn't specific "There will be a difference
Null Hypothesis ­ No significant change "There will be no difference...…read more

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Fewer Participants needs
+ The participants are the same so less time consuming
+ Not as big of a sample size
- Order effects
- Demand Characteristics
Independent Group Design ­ Split into two separate groups, both in different conditions this is used
to compare two sets of results.
+ Less chance of order effects
+ Can use same stimulus materials
No control over participant variables (eg.…read more

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Unstructured Observation ­ No decision beforehand so records nothing, relies on memory recall.
Naturalistic Observation ­ Researcher doesn't manipulate the setting as they won't to observe the
natural behaviour.
Open Questions ­ Participant is free to write the answers they wont to give, this is a detailed
Closed Questions ­ Answers given such as tick boxes or a list of suggestions, this is a limited
approach and heavily influenced by the researcher.…read more

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Cannot be used with nominal data (Categories)
Good and Bad points about MEDIAN:
+ The median is not affected by extreme values
Not all the data is used, so the median may misrepresent the data
Good and Bad points about MODE:
+ It is the only measure of central tendency that can be used for nominal data (Categories)
Can be several or no modes
Range ­ Lower the range the more reliable (highest ­ lowest=) (8-6=2)
+ Easy to analyse ­ Affected by extreme values…read more

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Strengths & Weaknesses of Content Analysis
+High ecological validity because based on what people do.
+Can be replicated easily because sources are publicly available.
-Observer bias reduces objectivity.
-Likely to be biased because sample will have particular characteristics eg. Drawn from one historical
period or from one culture.…read more


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