def get_sample_mean_var(df, col):
    """Calculate sample mean and sample variance of a 1-d array (or Series).

    Parameters
    ----------
    df: Pandas DataFrame

    col: str
        Column from df with numeric data to be plotted

    Returns
    -------
    tuple: (sample mean (float), sample variance (float))
    """

    # by default np.var returns population variance.
    # ddof=1 to get sample var (ddof: delta degrees of freedom)
    data = df[col]
    return data.mean(), data.var(ddof=1)