STATS 250 Lecture 3: STATS 280 NOTES 9:15
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STATS 250 Full Course Notes
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Stats 280 notes 9/15/2016: basic idea: the xth percentile is a number such that x percent of the data is less than that number, ex: say a class takes a midterm. The 90th percentile of a midterm scores would be the score where 90 percent of the class got lower, and 10 percent got higher: the exact definition of a percentile is tricky. Not always one of the numbers in the data set is equal to the xth percentile. Percentile: exact definition: let l be a list of numbers. The xth percentile is the smallest number q in l such that at least x percent of the numbers are less than or equal to x: ex: l = [5,7,16,2,-4,7]. Reorder: -4, 2, 5, 7, 7, 16. There are 6 numbers so each one is 16. 67 percent of the data set. It is the smallest number that is greater than or equal to at least 25% of the list.
