1. Displaying Data with Graphs
Dot Plot
Stemplot

2. Describing a Graph
Center
Shape
Spread

3. Center
If you had to pick a single number to describe all the data – the center would be the best.
It’s in the middle!
Median – Half the numbers are larger & half are smaller.
Mean – average of the numbers

4. Shape Are there any peaks? Is it skewed? Where is the tail?
Mode – occurs the most often.
Is it skewed? Where is the tail?
Skewed right – the tail is to the right
Skewed left – the tail is to the left

5. Shape – Are there modes? Bimodal Unimodal
How many bumps are in the graph? – Those are modes.

6. Uniform – Don’t appear to have. any mode. All bars are
Uniform – Don’t appear to have any mode. All bars are approximately the same height.

7. Symmetric?
Can you fold it along a vertical line through the middle and have the edges math pretty closely? If so, then it’s symmetric.

8. Shape –Skewed? It’s skewed to the side of the longer tail.
Positively Skewed or (Skewed right)
Negatively Skewed or (Skewed left)

9. Shape – Unusual Features
Are there any stragglers, or outliers?
Are there any gaps?

10. Spread – (Variation) How spread out is the data?
Range – Difference between highest & lowest
How spread out is the interquartile range?
IQR – the middle 50%
Is it tightly clustered around the center or spread out?

11. We looked at the base salaries of the CEOs of the 800 largest corporations in 1994.
Center – Centered around $500,000
Shape – Unimodal, Nearly Symmetric, Some high outliers
Spread – Majority are between $100,000 and 1,000,000. But there are a few with salaries between $2,500,000 and $3,000,000

12. Dotplots
How many classes are you taking?

13. Homework
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