| atLeast | gives a minimum estimated value for the approximate measurement. | 
    | atMost | gives a maximum estimated value for the approximate measurement. | 
    | min | where the measurement summarizes more than one observation
      or a range, supplies the minimum value
        observed. | 
    | max | where the measurement summarizes more than one observation
        or a range, supplies the maximum value
        observed. | 
    | confidence | The degree of statistical confidence (between zero and one) that a value falls within the range
        specified by min and max, or the proportion of observed values that fall within that range. |