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BiasBiasStage 6 - Year 11Stage 6 - Year 11

General MathematicsPreliminary

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Statistics - BiasBias happens when the survey results are affected by the poor choice in the

sample.For Example:

•Asking women if there should be a female only gym. Expected Answer:Yes

•Asking men if there should be a male only gym.

Expected Answer:No!•Asking student if teachers should be paid more.

•Asking teachers if teacher should be paid more.

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Yes Prime Minister Video

How to make a balanced survey

Statistics – Bias (Conscription)

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You know what happens: A nice young lady comes up to you.

Obviously you want to create a good impression.

You don't want to look a fool, do you?

So she starts asking you some questions:

Yes Prime Minister Video

Statistics - Bias (Conscription)

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•Mr. Woolley, are you worried about the number of young people without jobs? Yes

•Are you worried about the rise in crime among teenagers? Yes

•Do you think there is a lack of discipline in our Comprehensive schools? Yes

•Do you think young people welcome some authority and leadership in their lives?

Yes•Do you think they respond to a challenge?

YesWould you be in favour of

reintroducing National Service? [Conscription] Yes

Statistics - Bias (Conscription)

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•Mr. Woolley, are you worried about the danger of war? Yes

•Are you worried about the growth of armaments? Yes

•Do you think there is a danger in giving young people guns and teaching them how to kill?

Yes

•Do you think it is wrong to force people to take up arms against their will? Yes

Would you oppose the reintroduction of National Service [Conscription]? Yes

Statistics - Bias (Conscription)

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You don’t like this pair of jeans do you?

Should beDo you like this pair of jeans?

You like the Beatles music, don’t you?

Should beDo you like the Beatles music?

Statistics - Bias

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1. UndercoverageWhen some parts of the population are under represented.2. Non-responseA big problem in mail surveys.

3. Leading questionsGetting the answer you want.

Statistics – Bias (Causes)