2.2 What do samples tell us?Key Q-How do you use a sample?

Statistic-A number that describes a sample.

Parameter-A number that describes a population, this will be an estimate.

There are 22 kids in a class. 12 of those students play sports for the school.

The more samples you take the better parameter you can get.

Variability-The difference from sample to sample. How spread out they are.

There are 22 kids in a class. 12 of those students play sports for the school. If there is another class of 22 kids will 12 play sports?

A good sample = small bias, small variability.

To lower variability take large samples, to lower bias make samples as random as possible.

Confidence StatementHow confident you are that the sample is

true to the population.

Most common levels of confidence 90%, 95%, and 99%.

Margin of ErrorSimple version n being the total number in the

sample.

Good for 95% confidence level.

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1n

There are 22 kids in a class. 12 of those students play sports for the school.

We are 95% confident that all samples of

equal size will have between ______ and

_______ _________that ______________.

A sample of 183 sixteen year olds was taken and it was found that 30 of them did not pass the written part of their driving test the first time they took it. Construct a confidence statement.