def quality(stat_collector, cov_level):
    """
    Determine if variance is within an acceptable level.
    :param stat_collector: StatCollector object
    :param cov_level: acceptable limit for coefficient of variation
    :return: True if coefficient of variation is within acceptable limit
    """
    avg, stddev = stat_collector.eval(sampled=False)
    return stddev / avg < cov_level