Survey

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Transcript

AP Statistics HW: p.48-52 #39, 43,44, 45 Lab due next class Obj: to use variance and standard deviation Do Now: 1. Make a modified box plot for the # of home runs hit by Babe Ruth in each of his seasons as a Yankee: 54, 59, 35, 41, 46, 25, 47, 60, 54, 46, 49, 46, 41, 34, 22 2. Give the “five-number summary” for this data set. 3. Type the data into L1 and use the calculator to make a modified box plot. C 1, D 8 Standard Deviation • Give a numerical value to the spread of a distribution – If you give mean as the center, give standard deviation as the spread. – If you give the median as the center, give range as the spread. • To calculate std. dev. you must first calculate variance. Variance • Notation: s2 • For a data set with mean = x observations: x1, x2, …, xn and n 2 2 2 ( x x ) ( x x ) ... ( x x ) 2 2 n s 1 n 1 1 2 s ( xi x ) n 1 2 Standard Deviation (s) s= 1 2 ( x x ) i n 1 – Measures the spread about the mean, so should only be used when the mean is given as the measure of center. – (Handout of formulas) SOCS • For a strongly skewed distribution, the five-number summary is better to describe center and spread. • Mean and standard deviation are better for symmetric distributions. (Why?) • For strongly skewed distributions, very high or very low values can greatly affect the mean and standard deviation. *** Always plot your data first!!! *** Try Page 52 # 40 • Compare your answers with your partner