Range, Variance and Standard Deviation

Two classes can have the same average mark and still be very different. Spread measures how far values sit from the middle.

Range: largest minus smallest.
Variance: the average squared distance from the mean.
Standard deviation: the square root of the variance, in the same units as the data.

For a sample (some of a bigger group) divide by n - 1; for a whole population divide by n. NumPy uses the population version by default, so pass ddof=1 for a sample.

Examplepython

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Quick check

Two sets have the same mean. Set B has the larger standard deviation. What does that tell you?

B's values are more spread outB has more valuesB has the larger mean

Your turn: write the code

Print the sample standard deviation of the data, rounded to 2 decimals.

Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.

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