1. Percentile Rank Percentile rank (PR) refers to the position within a group that a person with a particular score is at. A person with percentile rank of 70 (Pr 70), means that he /she scored the same as or better than 70 percent of the group. Pr 50 means person scored same or better than 50 percent of group.

2. Percentile Rank – data on handout answers the question  What percentile rank tells us is within this group what position a baby’s weight represents.  8 lbs For example ?  And gives us some idea if this is high or low relative to group

3. Percentile Rank - data on handout birth weights Step One – list the weights (or scores) Score (Weight) FrequencyCumulative Frequency Relative Freq Percent 10 9 8 7 6 5 4

4. Percentile Rank - data on handout birth weights (30 babies) Step Two – how many births (or scores) at each weight Score (Weight) Frequency Number of babies 102 babies weigh 10 lbs 92 babies weigh 9 lbs 85 babies weigh 8 lbs 710 babies weigh 7 lbs 67 babies weigh 6 lbs 53 babies weigh 5 lbs 41 babies weigh 4 lbs

5. Percentile Rank – Relative Frequency Percent  Step Three – calculate what the number at each score represents of the whole  If 5 out of the 30 weigh 8 lbs, what does that weight represent as a percentage of the whole (30) ?

6. Percentile Rank - data on handout birth weights (30 babies) Step Three – relative frequency percent Score (Weight) Frequency Number of babies Relative Frequency Percent 1026.6 (7) 92 85 babies weigh 8 lbs 17.9 (18) 71033.3 (33) 6723.3 (23) 5310.0 (10) 413.3 (3)

7. Percentile Rank - data on handout birth weights (30 babies) Step Four – cumulative percent (Percentile Rank) Score (Weight) Frequency Number of babies Relative Frequency Percent Cumulative percent Percentile Rank 1026.6 (7)100 (has to be 100) 926.6 (7)94 85 babies weigh 8 lbs * 17.9 (18)87 (Pr87) * 71033.3 (33)69 6723.3 (23)36 5310.0 (10)13 413.3 (3)3

8. Percentile Rank  A baby weighing 8 lbs amongst this group (births in a week in Pleasantville) would be  Pr87 (at the 87 th percentile)  Which is the same (weight) as, or better than 87 % of the group (babies born that week).