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Unformatted text preview: Crib Sheet for Exam #1 Statistics 211 1 Chapter 1: Descriptive Statistics Sample Average Population Average x = 1 n n i =1 x i = 1 N N i =1 x i To caluclate the p th percentile x [ p ] : 1. Let x ( i ) refer to our data set in ascending order. 2. Let i p = np/ 100. 3. Find the first index i such that i > i p . 4. The p th percentile is then: x [ p ] = braceleftbigg x ( i- 1) + x ( i ) 2 if i- 1 = i p x ( i ) otherwise s 2 = 1 n- 1 summationdisplay ( x i- x ) 2 = 1 n- 1 parenleftBig summationdisplay x 2 i- ( x i ) 2 n parenrightBig Chebychevs Rule: The proportion of observations that are within k standard deviations ( p k ) of the mean is at least: p k = 1- 1 k 2 2 Chapter 2: Probability Multiplication rule Permutation Combination n 1 n 2 n 2 ... n k P k,n = n ! ( n- k )! ( n k ) = P k,n k ! = n ! k !( n- k )! For any two events A and B : P ( A B ) = P ( A ) + P ( B )- P ( A B ) The conditional probability of A given that B occurred ( P ( B ) > 0): P ( A | B ) = P ( A B ) P ( B ) Two events A and B are independent if P ( A | B ) = P ( A ) If A and B are independent then P ( A B ) = P ( A ) P ( B ) If A,B,C,D,... are mutually independent then P ( A B...
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This note was uploaded on 03/19/2012 for the course GEOG 305 taught by Professor Prout during the Spring '08 term at Texas A&M.
- Spring '08