Lect3_L6_L7_handout

Lect3_L6_L7_handout - lecture 3 Descriptive Statistics II...

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Unformatted text preview: lecture 3, Descriptive Statistics II Describing central tendency Review Relationships Among Mean, Median and Mode Measures of Variation Mean ( ctd) Geometric mean Variation Picking a Stock Measures of Variation Interquartile Range Box-and- whiskers plot Empirical Rule for Normals z-scores lecture 3, Descriptive Statistics II Describing central tendency Review Describing Central Tendency • A measure of central tendency represents the center or middle of the data • Measures of Central Tendency • Mean μ : The average or expected value • Median M d : The value of the middle point of the ordered measurements • Mode M o : The most frequent value lecture 3, Descriptive Statistics II Describing central tendency Review Relationships Among Mean, Median and Mode Measures of Variation Mean ( ctd) Geometric mean Variation Picking a Stock Measures of Variation Interquartile Range Box-and- whiskers plot Empirical Rule for Normals z-scores lecture 3, Descriptive Statistics II Describing central tendency Review Example 2’ from Lec2: The Car Mileage Case • For the first five car mileages recorded: 30.8, 31.7, 30.1, 31.6, 32.1, mean = 30 . 8 + 31 . 7 + 30 . 1 + 31 . 6 + 32 . 1 5 = 31 . 26 median = 31 . 6 . • If the first value is misrecorded as 3 . 08, mean’ = 3 . 08 + 31 . 7 + 30 . 1 + 31 . 6 + 32 . 1 5 = 25 . 72 median’ = 31 . 6 lecture 3, Descriptive Statistics II Describing central tendency Review Relationships Among Mean, Median and Mode Measures of Variation Mean ( ctd) Geometric mean Variation Picking a Stock Measures of Variation Interquartile Range Box-and- whiskers plot Empirical Rule for Normals z-scores lecture 3, Descriptive Statistics II Describing central tendency Review • The median is not affected by extreme values • “Extreme Values" are values much larger or much smaller than most of the data • The median is robust to extreme values • The mean is strongly affected by extreme values • The mean is sensitive to extreme values lecture 3, Descriptive Statistics II Describing central tendency Review Relationships Among Mean, Median and Mode Measures of Variation Mean ( ctd) Geometric mean Variation Picking a Stock Measures of Variation Interquartile Range Box-and- whiskers plot Empirical Rule for Normals z-scores lecture 3, Descriptive Statistics II Describing central tendency Review Mode • Value that occurs most often • Also robust to extreme values • Shoe store case, 9 was the mode based on the data you collected. One more data point came in: a giant person went to your store and asked a 16. How would that affect the mode? lecture 3, Descriptive Statistics II Describing central tendency Review Relationships Among Mean, Median and Mode Measures of Variation Mean ( ctd) Geometric mean Variation Picking a Stock Measures of Variation Interquartile Range Box-and- whiskers plot Empirical Rule for Normals z-scores lecture 3, Descriptive Statistics II Describing central tendency Relationships Among Mean, Median and Mode Relationships Among Mean, Median, and...
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This note was uploaded on 12/30/2009 for the course ISOM ISOM111 taught by Professor Anthonychan during the Fall '09 term at HKUST.

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Lect3_L6_L7_handout - lecture 3 Descriptive Statistics II...

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