Z-Score Outlier Detection

Problem

Detect outliers by z-score using the population standard deviation: return the indices i (ascending) where |(x_i - mean) / std| > threshold.

If the variance is 0 or the input is empty, return [].

Hint

Use the population standard deviation, then compare |z| against the threshold.

case 1

in: [[10,12,11,13,12,100],2]

expected: [5]

case 2

in: [[1,2,3,4,5],1.5]

expected: []

case 3

in: [[0,0,0,10],1.5]

expected: [3]

case 4

in: [[7,7,7],1]

expected: []

Starter codePython

def zscore_outliers(values, threshold):
    # Your code here
    pass

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