>>> def variance(data):
... # Number of observations
... n = len(data)
... # Mean of the data
... mean = sum(data) / n
... # Square deviations
... deviations = [(x - mean) ** 2 for x in data]
... # Variance
... variance = sum(deviations) / n
... return variance
...
>>> variance([4, 8, 6, 5, 3, 2, 8, 9, 2, 5])
5.76