Extreme Sampling Percentile This option enables you to specify a percentile to use for extreme sampling (for example, 10 indicates only phenotypes in the upper and lower 10% are used) of offspring for parent-offspring tests. Possible values that can be entered are 1, 5, 10, 25, or 50. Typing 50 results in no sampling. To Specify an Extreme Sampling Percentile: Make a selection using the drop-down menu.