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In Statistics, Measures of Central Tendency are numerical values that locate, in some sense, the centre of a set of data. The term average is often associated with all measures of central tendency.
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Understanding Central Tendency Properties in Statistics www.HelpWithAssignment.com
Numerical DataProperties & Measures Numerical Data Properties Central Tendency RelativeStanding Variation Mean Range Percentiles Interquartile Range Median Z–scores Variance Mode Standard Deviation www.HelpWithAssignment.com
n X i X X … X 1 2 n 1 i X n n Mean • Measure of central tendency • Most common measure • Acts as ‘balance point’ • Affected by extreme values (‘outliers’) • Formula (sample mean) • www.HelpWithAssignment.com
Raw Data: 10.3 4.9 8.9 11.7 6.3 7.7 X X X X X X X 1 2 3 4 5 6 1 X n 6 10 . . 8 9 11 . 6 3 . 6 . 30 • www.HelpWithAssignment.com
Numerical DataProperties & Measures Numerical Data Properties RelativeStanding Central Variation Tendency Percentiles Mean Range Median Interquartile Range Z–scores Mode Variance Standard Deviation • www.HelpWithAssignment.com
Median • Measure of central tendency • Middle value in ordered sequence • If n is odd, middle value of sequence • If n is even, average of 2 middle values • Position of median in sequence • Not affected by extreme values n 1 Positioning Point 2 • www.HelpWithAssignment.com
Median Example Odd-Sized Sample • Raw Data: 24.1 22.6 21.5 23.7 22.6 • Ordered: 21.5 22.6 22.6 23.7 24.1 • Position: 1 2 3 4 5 n 1 5 1 Positioning Point 3 . 0 2 2 Median 22 . 6 • www.HelpWithAssignment.com
Median Example Even-Sized Sample Raw Data: 10.3 4.9 8.9 11.7 6.3 7.7 Ordered: 4.9 6.3 7.78.9 10.3 11.7 Position: 1 2 34 5 6 n 1 6 1 Positioning Point 3 . 5 2 2 7 . 7 8 . 9 Median 8 . 30 2 • www.HelpWithAssignment.com
Numerical DataProperties & Measures Numerical Data Properties RelativeStanding Central Variation Tendency Range Mean Percentiles Interquartile Range Median Z–scores Mode Variance Standard Deviation • www.HelpWithAssignment.com
Mode • Measure of central tendency • Value that occurs most often • Not affected by extreme values • May be no mode or several modes • May be used for quantitative or qualitative data • www.HelpWithAssignment.com
Mode Example • No ModeRaw Data: 10.3 4.9 8.9 11.7 6.3 7.7 • One ModeRaw Data: 6.3 4.9 8.9 6.3 4.9 4.9 • More Than 1 ModeRaw Data: 21 28 28 41 4343 • www.HelpWithAssignment.com
Thinking Challenge You’re a financial analyst for Prudential-Bache Securities. You have collected the following closing stock prices of new stock issues: 17, 16, 21, 18, 13, 16, 12, 11. Describe the stock pricesin terms of central tendency. • www.HelpWithAssignment.com
Central Tendency Solution Mean n X i X X … X 1 2 8 i 1 X n 8 17 16 21 18 13 16 12 11 8 15 . 5 • www.HelpWithAssignment.com
Central Tendency Solution Median • Raw Data: 17 16 21 18 13 16 12 11 • Ordered: 11 12 13 16 16 17 18 21 • Position: 1 2 3 4 5 6 7 8 n 1 8 1 4 . 5 Positioning Point 2 2 16 16 Median 16 2 • www.HelpWithAssignment.com
Central Tendency Solution Mode Raw Data: 17 16 21 18 13 16 12 11 Mode = 16 • www.HelpWithAssignment.com
Summary of Central Tendency Measures Measure Formula Description Mean Balance Point X / n i Median ( n +1) Middle Value Position 2 When Ordered Mode none Most Frequent • www.HelpWithAssignment.com
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