def unbiased_sample_variance(observations, mean):
    """
    Compute the unbiased sample variance

    @param observations Iterable set of observations
    @param mean The estimated mean
    """
    n=1/ (len(observations) - 1)
    sample_=0
    for i in observations:
        sum0=(i-mean)**2
        sample_=sample_+sum0

    sample_var= n*sample_

    return sample_var