Coding Grandmaster · project 26 of 46 · premium, free for now

How spread out?

Write data_range(data), variance(data) and std_dev(data) (population versions, dividing by n). Print them for the data, rounding the standard deviation to 4 decimal places.

Learn

Two classes can have the same mean mark and very different spreads. The range is biggest minus smallest. The variance is the average of the squared distances from the mean, and the standard deviation is its square root, which puts the spread back in the original units. For the whole population you divide by n.

Your task

Write data_range(data), variance(data) and std_dev(data) (population versions, dividing by n). Print them for the data, rounding the standard deviation to 4 decimal places.

Stretch challenge

Use n - 1 instead of n (the sample version) and compare the two.

← Averages Quartiles and outliers →

Python

Press Run to see what your program prints.

Keep going in Coding Grandmaster

Averages

Write mean(data), median(data) and mode(data). If several values tie for most common, mode returns the smallest of them. Print all three for the list.

Start →27

Quartiles and outliers

Write quartiles(data) returning (q1, q2, q3) by the method above, and outliers(data) returning the sorted list of outliers by the 1.5 × IQR rule.

Start →28

A histogram in text

Count how many students got each grade and print one line per grade in alphabetical order, like A | #### 4.

Start →29

Do two things move together?

Write correlation(xs, ys) that returns Pearson's r rounded to 4 decimal places. Print it for study hours against marks.

Start →30

Scaling and z-scores

Write min_max(values) and z_scores(values) (use the population standard deviation). Both return lists with each number rounded to 2 decimal places.

Start →

Practise the idea

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