XL98: PERCENTRANK() May Appear to Return Incorrect Results

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To create an example of how the PERCENTRANK function returns different percentages when a number occurs more than once in the list of numbers, type the following in a new worksheet:

    A1: 1.00    B1: =PERCENTRANK($A$1:$A$4,A1)  (result in B is 1)
    A2: 0.75    B2: =PERCENTRANK($A$1:$A$4,A2)  (result in B is 0.666)
    A3: 0.50    B3: =PERCENTRANK($A$1:$A$4,A3)  (result in B is 0.333)
    A4: 0.25    B4: =PERCENTRANK($A$1:$A$4,A4)  (result in B is 0)
 
    A6: 1.00    B6: =PERCENTRANK($A$6:$A$13,A6)  (result in B is 0.857)
    A7: 0.75    B7: =PERCENTRANK($A$6:$A$13,A7)  (result in B is 0.571)
    A8: 0.50    B8: =PERCENTRANK($A$6:$A$13,A8)  (result in B is 0.285)
    A9: 0.25    B9: =PERCENTRANK($A$6:$A$13,A9)  (result in B is 0)
   A10: 1.00   B10: =PERCENTRANK($A$6:$A$13,A10) (result in B is 0.857)
   A11: 0.75   B11: =PERCENTRANK($A$6:$A$13,A11) (result in B is 0.571)
   A12: 0.50   B12: =PERCENTRANK($A$6:$A$13,A12) (result in B is 0.285)
   A13: 0.25   B13: =PERCENTRANK($A$6:$A$13,A13) (result in B is 0)
				

If you look at the percentage rank given to the value 1.00 in the first set of numbers and compare it to the percentage rank given to the value 1.00 in the second set of numbers, it may appear that the function is not working properly. However, this result is by design of the PERCENTRANK function. If the highest value occurs more than once, it must share the highest percentage rank, and, therefore, it will not be given a percentage rank of 1.00.