Percentile Rank Percentile rank PR refers to the

Percentile Rank – data on handout answers the question ØWhat percentile rank tells us

Percentile Rank - data on handout birth weights Step One – list the weights

Percentile Rank - data on handout birth weights (30 babies) Step Two – how

Percentile Rank – Relative Frequency Percent Ø Step Three – calculate what the number

Percentile Rank - data on handout birth weights (30 babies) Step Three – relative

Percentile Rank - data on handout birth weights (30 babies) Step Four – cumulative

Percentile Rank Ø A baby weighing 8 lbs amongst this group (births in a

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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.

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

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

Percentile Rank - data on handout birth weights (30 babies) Step Two – how many births (or scores) at each weight Score (Weight) Frequency 10 2 babies weigh 10 lbs 9 2 babies weigh 9 lbs 8 5 babies weigh 8 lbs 7 10 babies weigh 7 lbs 6 7 babies weigh 6 lbs 5 3 babies weigh 5 lbs 4 1 babies weigh 4 lbs Number of babies

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

Percentile Rank - data on handout birth weights (30 babies) Step Three – relative frequency percent Score (Weight) Frequency Number of babies Relative Frequency Percent 10 2 6. 6 (7) 9 2 6. 6 (7) 8 5 babies weigh 8 lbs 17. 9 (18) 7 10 33. 3 (33) 6 7 23. 3 (23) 5 3 10. 0 (10) 4 1 3. 3 (3)

Percentile Rank - data on handout birth weights (30 babies) Step Four – cumulative percent (Percentile Rank) Score (Weight) Frequency Cumulative percent Number of babies Relative Frequency Percent 10 2 6. 6 (7) 100 (has to be 100) 9 2 6. 6 (7) 94 8 5 babies weigh 8 17. 9 (18) 87 lbs Percentile Rank * 7 10 33. 3 (33) 69 6 7 23. 3 (23) 36 5 3 10. 0 (10) 13 (Pr 87) *

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