Lectures 3-4 Week2

1
Lectures 3-4 Week2

• Describing Data with Numerical Values
• (Chapter 2)

2
Terminology and Types of Measures

• Measures associated to Population Parameters
• Measures associated to a sample Statistics

Population
Sample
3
Two kinds of measures

• Measures of Location, center, position
• Measures of dispersion, shape, variability

4
Measures of location

• The mean
• Example
• The median
• Example
• The mode
• Example

5
Relationship between mean and median

• Median is robust
• If data symmetric, meanmedian
• If right-skewed data, mean shifts to right
• If left-skewed data, mean shifts to left. Median
  unchanged.

6
Measures of Dispersion

• Range
• Example
• Variance
• Shortcut formula
• Example
• Standard deviation
• Example
• Advantage has same unit as data.

7
Practical significance of standard deviation

• Chebychevs Theorem
• Example
• Empirical rule (symmetric data)
• Example
• Measures of relative standing
• Z-score, Outliers
• Example

8
Quartiles, Box-plots

• Q11st quartile
• Q2median
• Q33rd quartile
• IQRQ3-Q1
• Computing Formulae and Examples
• Box-plot
• Outliers