Controlling extraneous variables

Created by: Avneet Aulakh
Created on: 21-02-19 13:55

Extraneous variable

Variables that you are not interested in as part of an investigation or experiment but that could affect your results.

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Example of an extraneous variable and how you can control it

Noise and distraction e.g. Building work outside the room where an experiment is taking place - Make use of noise cancelling headphones

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Example of an extraneous variable and how you control it

Temperature e.g. no air conditioning in the room on a hot day - Make use of fans, open doors and windows.

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Location e.g. Experiment requiring an overnight stay in unfamiliar surroundings

Consider conducting the experiment in the participants own home and ask them to feed back with outcome.

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Lighting e.g. Poor lighting in a room where experiment requires identifying words or objects

Introduce additional lighting making sure all participants can see well enough to take part in the sm

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Why might researchers use control groups and matched pair tests?

It reduces the effect of extraneous variables

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Control group

A control group is used to test the effectiveness of a treatment. Random selection is used to select 2 groups of people.

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Example of a control group experiment

In an experiment to test a new drug, a test group is given the treatment and the control group is given no treatment or an inactive treatment ( called a placebo). Members of each group do not know whether they receive the active or inactive treatment

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...

So the results can be compared to see how effective the treatment is .

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Matched pair tests

Matched pair tests can be used to test the effects or a particular factor. Each individual in 1 group is paired with an individual in the 2nd group. The 2 individual have everything in common apart from the factor being studied.

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Other cards in this set

Card 2

Front

Noise and distraction e.g. Building work outside the room where an experiment is taking place - Make use of noise cancelling headphones

Back

Example of an extraneous variable and how you can control it

Card 3

Front

Temperature e.g. no air conditioning in the room on a hot day - Make use of fans, open doors and windows.

Back

Card 4

Front

Consider conducting the experiment in the participants own home and ask them to feed back with outcome.

Back

Card 5

Front

Introduce additional lighting making sure all participants can see well enough to take part in the sm

Back

View more cards

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Controlling extraneous variables