def rhoj(Sj, shatj):
    """
    Sample to Model Ratio (SMR) estimator (Eq. 5)

    Parameters
    ----------

    Sj
        random variables (i.e. data)
    shatj
        best estimate of the model. Should be same length as Sj

    Returns
    -------
    ndarray
        The Sample-to-Model ratio
    """
    return Sj / shatj