Outlier Count by 3-Sigma

Problem

Return the number of values farther than 3 population standard deviations from the mean. Return 0 when data is empty or the standard deviation is zero. With a population standard deviation, a sample smaller than about 11 points cannot produce an outlier.

Hint

Compare abs(x - mean) against 3 * sd.

Test cases

case 1

in: [[1,2,3,4,5]]

expected: 0

case 2

in: [[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,100]]

expected: 1

case 3

in: [[7,7,7,7,7,7,7,7,7,7]]

expected: 0

case 4

in: [[-100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]]

expected: 1

case 5

in: [[10,12,14,16,18]]

expected: 0

Starter codePython

def outliers_3sigma(data):
    # Your code here
    pass

5 test cases · run your code against them in the editor