Issues of reliablity, validity and sampling

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Define reliability.
How much we can depend on any measurement or the findings of a study.
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How do we test reliability?
If we repeat the measurement/test/study we can be sure that we would get the same result, or our measurement is unreliable.
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How are reliability and validity related?
If a measurement isn't reliable then a study can't be valid, however a measurement may be reliable but lack validity.
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What must we do when repeating an experiment to test it's reliablity and why?
It's essential that conditions are the same, otherwise any change in result may be due to changed conditions.
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Outline how we test reliability in observations.
They should be consistent, so 2 or more observers should produce the same record. The extent to which they agree is inter-rater or inter-observer reliability, calculated by dividing the agreements by the observations.
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What number suggests good inter-observer reliability?
0.8 or more.
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How can the reliability of observations be improved?
Through training observers in a coding system/behaviour checklist.
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Define internal reliability.
A measure of the extent to which something is consistant within itself.
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Define external reliability.
A measure of consistency over several occassions.
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Outline reliability regarding self-report techniques.
It concerns whether 2 interviewers produce the same outcome, called inter-reviewer reliability.
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How is a valid conclusion drawn from a study?
If any flaws are minimised.
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Define internal validity.
What goes on inside a study - whether the researcher did test what they intended to.
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Define external validity.
It concerns things outside a study - the extent to which the results can be generalised to other situations and people, also known as ecological validity.
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Give a weakness of all experiments regarding internal validity.
Internal validity is affected by extraneous variables which may act as an alternative IV, therefore changes in the DV are due to EVs, and conclusions about the effect of the IV on the DV are erroneous.
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Give a weakness of lab experiments regarding validity.
The contrived, artifical nature of the lab setting isn't relevent to the behaviour being observed in some cases and therefore it can't be generalised, which can be the same as field experiments.
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What is the most important weakness of all experiments regarding internal validity?
To consider issues, and whether the task was artifical and low in mundane realism, which reduces generalisability.
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Explain what affects observations in terms of internal validity.
They will not be valid if they coding system/behaviour checklist is flawed, and it's also affected by observer bias - what someone observes is influenced by expectations, which reduces the objectivity.
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Do observations have high ecological validity and why?
They're likely to have high ecological validity because they involve natural behaviours.
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Define face validity.
Does the test look as if it's measuring what the researcher intended to.
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Define concurrent validity.
Comparing a questionnaire with a previously established one. If the participants' performance on both tests show a high correlation, this is evidence of high concurrent validity.
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How is the external validity of self-report techiniques likely to be affected?
By the sampling strategies, which may create a biased sample.
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What size sample is preferred for research and why?
A small sample size because larger groups involve more time and money.
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How are samples obtained and why are they obtained this way?
Psychologists use sampling techniques which minimise cost while maximising generalisability.
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Name the 5 sampling techniques.
Oppertunity, volunteer, random, stratified & quota, and snowball.
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Outline and evaluate opportunity sampling.
Participlants are selected by using people who are most easily available. This is the easiest method but it's biased because the sample is drawn from a small part of the population.
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Outline and evaluate volunteer sampling.
Participants are selected by asking for volunteers. It can access a variety of participants which makes the sample representative, however they're biased because participants are likely to be motivated and/or with extra time on their hands.
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Outline random sampling.
All members of the population are identified and then individuals selected by the lottery method or using a random number generator.
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Give a strength and a weakness of random sampling.
It's potentially unbiased because all members of the population have an equal chance of selection, although the researcher may end up with a biased sample because people refuse to take part.
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Outline stratified and quota sampling.
Sub-groups within a population are identified, then a predetermined number of participants is taken from each proportion to their representation in the population.
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What is the difference between stratified sampling and quota sampling?
Stratified sampling uses random techniques, quota uses opportunity sampling.
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Give a strength and a weakness of stratified and quota sampling.
It's more representative, however selection within each sub-group may be biased.
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Give a strength and a weakness of snowball sampling.
It's useful when participants aren't easy to identify, but is prone to bias: researchers may only contact people within a limited selection of the population.
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Define population.
All the people whom a researcher wishes to make a statement about.
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What is the aim of a sampling technique?
To select a representative sample from a population in terms of characteristics.
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Why is representativeness important?
The importance of representativeness is the ability to generalise to the population, or else it's biased.
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Card 2

Front

How do we test reliability?

Back

If we repeat the measurement/test/study we can be sure that we would get the same result, or our measurement is unreliable.

Card 3

Front

How are reliability and validity related?

Back

Preview of the front of card 3

Card 4

Front

What must we do when repeating an experiment to test it's reliablity and why?

Back

Preview of the front of card 4

Card 5

Front

Outline how we test reliability in observations.

Back

Preview of the front of card 5
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