Notes 2 - (Continue Chapter 1 Examining Distributions 1.2...

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(Continue) Chapter 1: Examining Distributions 1.2 Describing Distributions with numbers: Center and Spread: To get a useful numerical description of a distribution, we need to have both some measure of center and some measure of spread. Measuring center: Provide some notion of what value the distribution is grouped around. The most common measures are the mean and median. The Mean x : also called the arithmetic average, represent the balance point for quantitative data. x = x 1 + x 2 + ... + x n n = x i i = 1 n n This is the sum of the observations divided by the sample size. Example: This data set is the first 11 games of the men’s basketball team. DATE OPPONENT W/L SCORE ATTEND ------------ -------------------- --- ----- ------ 11/16/09 JACKSONVILLE W 87-61 6493 11/18/09 STETSON W 80-38 6525 11/21/09 at Mercer W 89-50 3200 11/24/09 at Florida L 52-68 11239 11/26/09 vs Iona W 54-49 2149 11/27/09 vs Alabama W 60-51 1915 11/29/09 vs Marquette W 57-56 2225 12/2/09 at Ohio State L 64-77 13514 12/6/09 FIU W 82-62 5168 12/15/09 GEORGIA STATE W 62-55 5281 12/17/09 AUBURN W 76-72 6063 Example: Find the mean score of the first 11 games that FSU played in Fall 09. x = 87 + 80 + 89 + 52 + 54 + 60 + 57 + 64 + 82 + 62 + 76 11 = 763 11 = 69.3636
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Median: is the middle value this value and 50% lie abov Steps: 1. Arrange the data valu 2. If the number of data observation on the o (n+1)/2 observation 3. If the number of data center observations (n+1)/2 from the bo *Note that the formula (n+1 median in the ordered list. Odd data set -Example : fin Home games=(6493, 6 x = M= Even data set-Example : fin from home games. Away games= (3200, 11239 x = M= Mean vs. Median The mean is GREATLY affected The median is NOT affected by If the mean and median are (a symmetric. If mean<median, distribution If mean> median, distribution *NOTE: when it is skewed the e of an ordered data set. (i.e. 50% of the value ve this value). es in an ascending order (from smallest to lar
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Notes 2 - (Continue Chapter 1 Examining Distributions 1.2...

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