1. 3.1 Graphical Displays of Data

2. Example 1 Describe each distribution Uniform Mound Shaped U-Shaped / Bi-modal Skewed (left) Skewed (right)

3. Example 2 Identify the bin width and number of bins. Find a formula to relate your answers. 100120140160 10 20 30 Bin Width: 10 Number of Bins: 6 Bin Width = High – Low # Bins 10 = 160 – 100 6

4. Example 3 What intervals does this histogram show? 100120140160 10 20 30 You would think the intervals are 100 to 110, 110 to 120, … 150 to 160 THEY AREN’T !!!  Bottom end of intervals is the number that round what you think it should be, top end of the intervals … add the bin width to the bottom 99.5 to 109.5, 109.5 to 119.5, … 149.5 to 159.5 In general, add one more decimal place then the initial data.

5. Example 4 What would happen to the graph if the bin widths were doubled/halved? 100 120 140160 10 20 30 100 120 140160 20 40 60 Changing the bin width may DRAMATICALLY change the appearance of the data.