1. Describing Data with Numerical Values (Chapter 2)
Lectures 3-4 Week2
Describing Data with Numerical Values
(Chapter 2)
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Chapter 2

2. Terminology and Types of Measures
Measures associated to Population: Parameters
Measures associated to a sample: Statistics
Population
Sample
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Chapter 2

3. Two kinds of measures Measures of Location, center, position
Measures of dispersion, shape, variability
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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.
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Chapter 2

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

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

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