The average test score of those selected is the average of the scores that are at least 0.842. To determine this, use Excel’s DAVERAGE function. To do so, put the heading Score in cell A3, generate the 1000 test scores in the range A4:A1003, and name the range A3:A1003 Data. In cells C3 and C4, enter the labels Score and 0.842. (The range C3:C4 is called the criterion range.) Then calculate the average of all applicants who will be hired by entering the formula

DAVERAGE(Data, “Score”, C3:C4) in any cell.

This average should be close to the theoretical average, 1.40. This formula works as follows. Excel finds all observations in the Data range that satisfy the criterion described in the range C3:C4 (Score 0.842).

Then it averages the values in the Score column (the second argument of DAVERAGE) corresponding to these entries. Look in online help for more about Excel’s database functions.

c. What information would you need to determine an

“optimal” selection ratio? How could you determine an optimal selection ratio?