Hello, I observed that there are 2 standard deviation functions in the scipy/numpy modules: Numpy: http://docs.scipy.org/doc/numpy/reference/generated/numpy.std.html#numpy.std Scipy: http://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.std.html#sci... What is the difference? There is no formula included within the docstrings. I suppose that np.std() is for the whole population and scipy.std is designed for a smaller sample in the population. Is that true? Are there any functions for calculating the mean bias error (MBE)? I am looking for forumla 3 in http://en.wikipedia.org/wiki/Mean_squared_error#Examples The function mbe seems to implement it here: http://cerea.enpc.fr/polyphemus/doc/atmopy/public/atmopy.stat.measure-module... I also found a implementation of root mean square error (RMSE), as function rms, in: http://www2-pcmdi.llnl.gov/cdat/source/api-reference/genutil.statistics.html Unfortunately, cdat cannot be installed natively on Windows. Thanks in advance, Timmie