1. AP Statistics Objective: Students will be able to construct and determine when to use bar charts, pie charts, and dot plots. (Histograms)

2. Vocabulary distributionThe distribution of a variable tells us what values the variable takes and how often it takes these values. There are different ways to show the distribution of data. (Organizing Data)

3. Bar Charts Bar charts help us compare the sizes of groups by looking at the height of the bars in each category. A B C D 20 15 10 5 0

4. Attributes of a “good” chart Title Axis Labels Consistent Scale

5. Pie Charts Pie charts help us see what part of the whole something represents. (Percents)

6. 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

7. 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

8. Dot Plots To make a dot plot draw a horizontal line to represent the variable and label a number scale for the values of the variables underneath the line. The values only need to cover the range of the data.

9. A B C D 20 15 10 5 0 Comparing Charts and Plots

10. Histograms Each row of a stemplot represents a number of data points found in a range. What kind of ranges might a stemplot have? Histograms have the same general idea, but histograms are more flexible in terms of the ranges. Ranges have equal width

11. Constructing Histograms Constructing Histograms on the TI-83 and by hand. Specify the classes precisely so that each observation (value) falls into exactly one class. Use the best judgment possible to create a graph that shows the distribution. Make sure all bars are the same width.

12. Histograms Histograms may be less useful than stemplots because you can’t see the actual data.

13. Histograms Ranges for histograms generally include the lower end of the range, but does not include the upper end of the range

14. Using the TI-83 to make histograms The TI-83 can be used to make histograms, and will allow you to change the location and widths of the ranges.

15. Using the TI-83 to make histograms Start by entering data into a list Example: Enter the presidential data from page 19 into any list; in this case, we will use L 1

16. Using the TI-83 to make histograms Choose 2 nd :Stat Plot to choose a histogram plot Caution: Watch out for other plots that might be “turned on” or equations that might be graphed

17. Using the TI-83 to make histograms Turn the plot “on”, Choose the histogram plot. X-list should point to the location of the data.

18. Using the TI-83 to make histograms Under the “Zoom” menu, choose option 9: ZoomStat

19. Using the TI-83 to make histograms The result is a histogram where the calculator has decided the width and location of the ranges You can use the Trace key to get information about the ranges and the frequencies

20. Using the TI-83 to make histograms You can change the size and location of the ranges by using the Window button Press the Graph button to see the results

21. Using the TI-83 to make histograms Voila! Of course, you can still change the ranges if you don’t like the results.

22. Outliers An outlier in any graph of data is an individual observation that falls outside the overall pattern of a graph.Center Center refers to the value that approximately divides the observations in half. (Half Larger/Half Smaller) Usually median or mean

23. Spread The spread is the extent of the data from smallest to largest value. (Ignoring Outliers) Ex: 23 to 67 Range is the difference between the smallest and largest values. Ex 67 – 23 = 44

24. Homework Read from page 13 (Example 1.3) to page 15 (Exercises) Do Exercise 1.4 thru 1.8