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Unformatted text preview: Descriptive Statistics Measures of Central Tendency You should be able to . . . • Define the term measure of central tendency • Define and compute: –Mode –Median –Mean • Compare the measures of central tendency when distributions are skewed Measures of Central Tendency • Measures that describe where the center of a distribution of scores is located • Measures that represent the most typical or most representative scores in a distribution Three Measures of Central Tendency Mode Median Mean Mode • The most frequently occurring score in a frequency distribution • Simplest measure of central tendency Example: Friends Extro/Introversion What are the modes? What are the modes? What are the modes? • Remember: The MODE is the class, NOT the frequency What is the mode? What is the mode? • There are two modes: 2 and 10 Median • The point in a frequency distribution that separates the top 50% of the scores from the bottom 50% 1 2 3 4 5 6 7 8 9 10 11 12 13 • The score at the 50th percentile • Half of the scores lie above the median; half of the scores lie below the median Example: Odd number • Nine observations: 4 6 5 9 8 10 11 7 3 1. Order the observations 4 6 5 9 8 10 11 7 3 1. Order the observations 4 6 5 9 8 10 11 7 3 1. Order the observations 4 6 5 9 8 10 11 7 3 3 4 5 6 7 8 9 10 11 2. Find the middle position Middle position = (number of scores +1)/2 Middle position = (9+1)/2 = 5 3 4 5 6 7 8 9 10 11 2. Find the middle position Middle position = (number of scores +1)/2 Middle position = (9+1)/2 = 5 3 4 5 6 7 8 9 10 11 2. Find the middle position 14 15 16 17 18 19 20 Middle position = (number of scores +1)/2 Middle position = (9+1)/2 = 5 3 4 5 6 7 8 9 10 11 2. Find the middle position 2....
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This note was uploaded on 08/22/2011 for the course PSY 207 taught by Professor Pfordesher during the Fall '07 term at SUNY Buffalo.
 Fall '07
 Pfordesher

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