To compare two distributions, can construct a back-to-back stem-and-leaf display • Uses the same stems for both • One leaf is shown on the left side and the other on the right 135
Sample Back-to-Back Stem-and-Leaf Display 136
Back-to-Back histogram Display Comparing Two Distributions with back-to- back bar charts 137
Back-to-Back histogram Display Comparing Two Distributions with back-to- back bar charts 138
Scatter Plots • Used to study relationships between two quantitative variables • Place one variable on the x-axis • Place a second variable on the y-axis • Place dot on pair coordinates 139
Types of Relationships • Linear : A straight line relationship between the two variables • Positive : When one variable goes up, the other variable goes up • Negative : When one variable goes up, the other variable goes down • No Linear Relationship : There is no coordinated linear movement between the two variables 140
A Scatter Plot Showing a Positive Linear Relationship 141
A Scatter Plot Showing a Little or No Linear Relationship 142
A Scatter Plot Showing a Negative Linear Relationship 143
Misleading Graphs and Charts: Scale Break Mean Salaries at a Major University, 2004 - 2007 Break the vertical scale to exaggerate effect 144
145 Misleading Graphs and Charts: Horizontal Scale Effects
146 You can use simple mathematical operations (like averages) to create nonsensical “facts” that can drive whatever agenda you’d like. Example: the average wealth of the citizens of a particular town is $100,000, therefore they don’t need any government assistance. (The town consists of 1 stingy millionaire and 9 homeless people.)
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- Fall '19
- Frequency, Frequency distribution, Bar chart, Histogram