Percentiles

 -scores of students are arranged in rank order from lowest to highest

 -the scores are divided into 100 equally sized groups or bands

 -the lowest score is "in the 1st percentile" (there is no 0 percentile rank)

 -the highest score is "in the 99th percentile"

  (you can't score in the 100th percentile because you can't beat your own score)

If you "scored in the 66th percentile", you scored "as well as or better than" 66% of the group.

If your score was the same as "the mean" for that test, you scored in the 50th percentile.(The mean is the middle of a distribution, and the 50th percentile is the same...the middle of the group.)

If 700 people took a test, how many people would be in each percentile band?

   (Divide 700 by 100 bands/ranks)

If only one student is taking the diagnostic achievement test, how do we determine his/her percentile ranking? Who do we compare him/her against?  (The norm groups...kids who have taken the test previously... provided by the test)

-scores of students are arranged in rank order from lowest to highest

 -the scores are divided into 10 equally sized groups or bands (instead of 100 as with percentiles)(Or divide the percentiles into bands of 10 percentile ranks)

the lowest score is "in the 1st decile"

the highest score is "in the 10th decile"

 -scores of students are arranged in rank order from lowest to highest

 -the scores are divided into 4 equally sized groups or bands

  (Or divide the percentiles into bands of 25 percentile ranks)

-the lowest score is "in the 1st quartile"

-the highest score is "in the 4th quartile"