1. Lesson on Data Displays

2. Dot Plot
A dot plot can make some observations easier, especially gaps and outliers. It gives an overall sense of the data’s center, spread, and shape. It is like a number line, but you don’t have to start at zero.

3. Dot Plot

4. Frequency Table
A frequency table is a list of categories that classifies the number of occurrences in each category.

5. Two-Way Frequency Table
A two-ways frequency table displays the distribution for two categorical variables.
Athlete
Non-Athlete
Agree 10 5
Disagree 7 4

6. Two-Way Frequency Table
A two-ways frequency table displays the distribution for two categorical variables.
Athlete
Non-Athlete
TOTAL
Agree 10 5 15
Disagree 7 4 11 17 9 26

7. Categorical Data What Do You Call Carbonated Drinks? STATE “Pop”
“Soda”
“Coke”
Other
California
4566
968
323
446
New York
3433
493
1385 44
Georgia
455
456
5038
445
Main
584
3924
453
4523

8. Stem-and Leaf Plots
A stem-and-leaf plot is a graph that organizes the leading digits of data as stems. The remaining digits becomes leaves. DATA: 12, 13, 21, 27, 33, 34, 35, 37, 40, 40, 41 KEY: 1|2 = 12

9. Stem-and Leaf Plots
DATA: 23.3,  24.1,  24.8,  24.8,  25.0,  25.3,  25.6,  25.9,  26.3,  26.3,  27.1

10. Histogram
A histogram is a type of graph that uses vertical bars to display continuous data. Unlike dot plots, which display single values, the bars of a histogram (sometimes called bins/classes) may have any fixed width.

11. Histogram

12. Histogram

13. What makes a good histogram?
Title
Label the x and y-axis
Have a correct scale:
the x-axis = the data values
The y-axis = the frequency values (how often the data may appear)
All of the bins are touching each other

15. There is no single “correct” bin width for a histogram
There is no single “correct” bin width for a histogram. The width of a histogram’s bins can affect how well it shows the center, spread, shape, and outliers of the corresponding data.

16. How to create a histogram
1) Decide the number of bins/classes. There is no wrong or right answer. It depends on the data.
2) Find the width of the bin.
𝑤𝑖𝑑𝑡ℎ= ℎ𝑖𝑔ℎ𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒 −(𝑙𝑜𝑤𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒) # 𝑜𝑓 𝑐𝑙𝑎𝑠𝑠𝑒𝑠
3) Create a frequency table
4) Create a histogram

17. Example
Teachers’ ages: 21, 22, 25, 32, 34, 45, 48, 49, 49, 49, 51, 52, 52, 56, 58, 60, 61, 61, 67