class BooleanColumn extends AbstractColumn<BooleanColumn, Boolean> implements BooleanFilterSpec<Selection>,
        BooleanMapUtils,
        CategoricalColumn<Boolean>,
        BooleanFillers<BooleanColumn>,
        BooleanFilters {

  public double proportionTrue() {
    return (double) countTrue() / (size() - countMissing());
  }

  private  BooleanColumn(String name, ByteArrayList values);

}