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Research Methods
Aims and Hypotheses

Aim: general purpose of an investigation, what you are trying to achieve in the
Hypothesis: a precise, testable statement or prediction about the expected outcome of an
Null Hypothesis: a prediction that states that results are due to chance and are not

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1. Repeated Measures: Testing the same group of people in different conditions, the
same people are used repeatedly.

Fewer people are needed.
Avoids the problem of participant variables

Order effects are more likely to occur

2. Independent groups: Testing separate groups of people - each group…

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Counterbalancing: alternating the order in which participants perform in different
conditions of an experiment. E.g. group 1 does 'a' then `b'; group 2 does 'b' then 'a' to
eliminate order effects.
Randomisation: material for each condition in an experiment is presented in a
random order; this is also to prevent…

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Standardized instructions ­ each participant must be given exactly the same instructions,
ideally by the same person and in the same way. If some participants were given instructions,
which included demonstrations of how to do a task, and others were not, this could affect the
results. One way of ensuring…

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Some people may be unable to give informed consent, such as children or those with special needs.
Nevertheless, they must be asked if they are willing to help you, but full consent must be gained
from whoever is responsible for that person, such as a parent or career. These people…

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5. Systematic sampling: Chooses subjects in a systematic way, for example,
every 10th person from a list or register.
To being with, all population is involved; this is an improvement of opportunity and volunteer sampling.
Not everyone has an equal chance of taking part so unrepresentative
Still possible to…

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2. Concurrent validity: This involves comparing a new test with an already established
test designed to measure the same thing. If scores are similar, then the new test is

3. Predictive validity: This involves checking validity by seeing if future behaviour is
consistent with what we could predict based…

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Ratio level of measurement

Ratio data provides us with the strongest and most precise method of measurement.
Ratio scales have a true zero, e.g. time in seconds and distance in cm. negative numbers
have no meaning.

Descriptive statistics

Quantitative research: gathers data in numerical form and is concerned with making…

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Does not represent all scores

Range: difference between largest and smallest scores, quote biggest and smallest scores,
or take smallest from biggest score and quote this figure.
Easy to calculate
Use with ordinal, interval or ratio level data
Does not indicate how tightly/widely spread scores are

Standard deviation: average variation…

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1. Type 1 error: the null hypothesis is wrongly rejected- the results are, in fact, due to chance factors
and not due to the manipulation of our variable. The reason for a type 1 error is that a too lenient
level of significance has been used (e.g. p0.01).
2. Type…


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