AF Sections 2.5-2.6 handouts

AF Sections 2.5-2.6 handouts - STAT 2000 Measures of...

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1 STAT 2000 Sections 2.5-2.6 Measures of Position Statistics: The Art and Science of Learning from Data Agresti-Franklin Measures of Position Percentiles The pth percentile is the value below which you have p% of the data. Example : If a value lies at the 30 th percentile, then approximately 30% of the values are less than this value, and approximately 70% of the values are greater than this value. Notation : P 30 is the 30 th percentile. If John graduated at the 78th percentile in a class of 876, approximately how many students ranked below John? Joan learned that she would graduate ranked 47th (from the top) in a class of 876. Joan graduated at the _____ percentile of her class. Measures of Position: Quartiles Quartiles divide the data into 4 equal parts. 25% | 25% | 25% | 25% Q1 Q2 Q3 Q1: First Quartile is the 25 th percentile. (25% below and 75% above) Q2: Second Quartile is the 50 th percentile. (50% below and 50% above) Q2 is also the median. Q3: Third Quartile is the 75 th percentile. (75% below and 25% above) 25% | 25% | 25% | 25% Q1 Q2 Q3 P 25 P 50 P 75 median D t Finding Quartiles First find the median. Then find the middle value of the upper and lower halves. Remember the data must be in order! Data: 20 19 30 18 17 22 Data 20 19 30 18 17 22 23
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