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Describing Data with Numerical Values (Chapter 2)

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Presentation on theme: "Describing Data with Numerical Values (Chapter 2)"— Presentation transcript:

1 Describing Data with Numerical Values (Chapter 2)
Lectures 3-4 Week2 Describing Data with Numerical Values (Chapter 2) 1/18/2019 Chapter 2

2 Terminology and Types of Measures
Measures associated to Population: Parameters Measures associated to a sample: Statistics Population Sample 1/18/2019 Chapter 2

3 Two kinds of measures Measures of Location, center, position
Measures of dispersion, shape, variability 1/18/2019 Chapter 2

4 Measures of location The mean The median The mode Example 1/18/2019
Chapter 2

5 Relationship between mean and median
Median is robust If data symmetric, mean=median If right-skewed data, mean shifts to right If left-skewed data, mean shifts to left. Median unchanged. 1/18/2019 Chapter 2

6 Measures of Dispersion
Range Example Variance Shortcut formula Standard deviation Advantage: has same unit as data. 1/18/2019 Chapter 2

7 Practical significance of standard deviation
Chebychev’s Theorem Example Empirical rule (symmetric data) Measures of relative standing Z-score, Outliers 1/18/2019 Chapter 2

8 Quartiles, Box-plots Q1=1st quartile Q2=median Q3=3rd quartile
IQR=Q3-Q1 Computing Formulae and Examples Box-plot Outliers 1/18/2019 Chapter 2


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