11.11 A company has administered a screening aptitude test to 20 new employees over a 2 year period. The record of scores and data on which the person was hired are shown below.

1=4=08 75 9=21=08 72 12=9=08 81 5=10=09 91 3=9=08 74 10=4=08 77 1=22=09 93 7=17=09 95 6=3=08 71 10=9=08 76 1=26=09 82 9=12=09 90 6=15=08 76 11=1=08 78 3=21=09 84 10=4=09 92 8=4=08 98 12=5=08 80 4=6=09 89 12=6=09 93 Assuming that these scores are the primary criterion for hiring, do you think that over this time period the screening procedure has changed, or the personnel agent has changed, the supply has changed, or what? Use all nonparametric procedures that are appropriate.