How to do psychological research


Null hypothesis, H0

Hypothesises that there will be a negative effect of the independent variable

Example: alcohol does not increase reaction times

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Alternative / experiemental hypothesis, H1

Hypothesises that there will be a positive result of the independent variable

Example: Alcohol increases reaction time

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There must be a reasonable way of showing that the hypothesis is wrong, this makes them falsifiable

Example: All swans are white

Is falsifiable because it can be disproven by finding a swan of a different colour

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Directional / one-tailed hypothesis

Specifies the direction of the results

Examples: Alcohol increases reaction times

Alcohol decreases reaction times

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Non-directional / two-tailed hypothesis

Hypothesises that there will be an effect but doesn't specify what it will be

Example: Alcohol will impact on reaction time

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Qualitative research methodologies

For questions that can't be answered with scientific methods

Interviews, focus groups, observation

Investigate experiences, meanings, processes

Can be used to form testable hypotheses or to study particular issues that are unsuited to quantitative designs

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Used to determine cause-and-effect

Measure the effect of one variable on another

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How one variable affects another

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Independent variable

Used in experiments

The variable that the researcher manipulates or changes 

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Dependent variable

The object/thing/result that the researcher measures after manipulating the independent variable

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Within-subjects / repeated measures

Type of experiment

All participants are exposed to all levels or conditions of the independent variable

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Number of participants in an experiment, sample size

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Dividing the participants of an experiment to do the levels in different orders to avoid order effects

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Between subjects / independent designs

Type of experiment

Different people are exposed to different levels of the independent variable

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Control group

The results of the experimental group are compared to those of a control group which was not exposed to the independent variable

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The Hawthorne effect

A type of reactivity in which individuals modify an aspect of their behavior in response to their awareness of being observed

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The placebo effect

Expectation effects result

Example: I expect the alcohol to slow my reaction time, therefore my reaction time is slowed 

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The participants of the experiment are unaware of which group they are in and which independent variable they have been exposed to

Prevents the placebo effect

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Neither the participants of the experiment OR the researcher are aware of which subjects are in which groups and which independent variables they are exposed to

Prevents experimenter bias

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Observational designs

Are not about establishing cause-and-effect

We don’t manipulate anything, we just measure existing behaviour/conditions

Used for studying topics where it would be difficult or unethical to manipulate conditions

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Positive correlation

If one score increases so does the other

Example: Higher amounts of alcohol makes for better reaction times

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Negative correlation

If one score increases the other decreases

Example: Higher amounts of alcohol makes the reaction time slower

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Subsection of a population

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Random sampling

Participants should be randomly assigned to avoid extraneous variables becoming confounds

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Extraneous variables

Variables that will impact the experiment in some way and are unavoidable but that are outside of the researcher's control and not part of the variables which are being examined

For example: In the alcohol experiment, the person's age, tiredness levels, concentration, etc also impact on their reaction times

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When extraneous variables differ systematically by level of the independent variable

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Convenience/opportunity sampling

Sampling from the most convenient subjects available, with limited randomness and variation, which often tends to not be representative of the whole population

Example: Conducting a psychology study where all the subjects are psychology students, though their area of study is irrelevant

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A test, study, or experiment will get the same results if it is repeated

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Repetition of experiments and studies should be replicable in the sense that they should attain the same results if they are repeated

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If the test is measuring what it is supposed to and is doing so accurately

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