It is sadly really inconsistent. The stdlib statistics has two separate functions, stdev for sample and pstdev for population. Numpy and pandas both have .std()

It is sadly really inconsistent. The stdlib statistics has two separate functions, stdev for sample and pstdev for population. Numpy and pandas both have .std() with ddof (delta degrees of freedom) as a parameter, but numpy defaults to 0 (population) and pandas to 1 (sample).