1. Section 1.1 Part 2
AP Statistics
CASA

2. Quick and Dirty Graphs
Sometimes we would like to get a quick idea of the distribution of a variable from a data set
Two of the best graphs are
Stemplots
Dotplots

3. Dotplots Horizontal axis with either quanitative scale or categories
Each dot represent one data point
If more than one data point has the same value, “stack” the dots

4. Stemplots
Each data point is represented by a single number (leaf) associated with a more significant number (stem)
Rounding can help the shape of the distribution become more noticeable.

5. Describing Distributions
Center: Where is the middle of the data (middle is intentionally vague)
Spread: How much variation is present
Shape: What shape does the data take
Are there Outliers
Outliers are atypical data points
Outliers fall outside the overall pattern of the graph

6. Describing Shape
Uniform
Bell
Symmetric
Skew
Bimodal

7. Uniform 1
13489 2 3 4 5 6 7 8 9 10

8. Bell 1 2 13 3
135 4
1357 5
135579 6 7 8 9 10

9. Skew 1 2
1357 3 4
135579 5 6 7 13 8 9 10

10. Bimodal 1 2
1357 3 4
135579 5 6 13 7 8 9 10

11. Assignment
Problem 1.7 – 1.11, The Practice of Statistics