Write down three observations about the data shown.

1. Write down three observations about the data shown. • Write down two more observations by looking at the same data in graphical form. • Which was easier to look at, the table or the graph?

2. Statistical Graphs of Data:Dot Plot and Histograms AA1 CC Unit 7

3. 3 Types of Graphs • Dotplot – each dot represents a data point • Histogram – data points are put into a range 3.Boxplot – uses the 5 number summary

4. Dotplot Advantages Disadvantages Takes a long time to construct if many data points • See every data point • Quickly see the range (highest and lowest point) • Easy to see the mode (most frequent data point)

5. Example #1 • Create a dot plot for the following data: 52, 43, 61, 69, 69, 55, 62, 52, 47, 54, 69, 43, 53,48

6. How to construct a histogram • Determine the lowest and highest data point • Decide on the length of the bars based on #1, each bar must be the same length • Example: if the data goes from 42 to 98, then use categories from 40-50, 50-60, 60-70, 70-80, 80-90 and 90-100 (don’t want too many bars) • Put the data points into each range • If a data point lies on a break line, it goes to the higher category. • The height of the bar corresponds to how many data points are in that category (frequency).

7. Histogram Advantages Disadvantages Can’t see every data point, only the ranges they are in • Easy to create • Quickly see the range (highest and lowest) • Easy to see the shape of data

8. Example #2 • Create a histogram for the following data: 52, 43, 61, 69, 69, 55, 62, 52, 47, 54, 69, 43, 53,48

9. Example #3 • The following data are quiz grades for an Algebra class. Create a histogram to display the data. 94, 80, 90, 83, 86, 76, 100, 98, 73, 88, 75, 72, 59, 58, 100, 65, 90, 81, 46, 100, 66, 76, 99, 95, 80, 55

10. Classwork! • Handout • And Grade Conferences!