Statistics Displaying Categorical Data Stemplots Frequency Tables Histograms Time Plots … and why Graphical displays of data are increasingly prevalent in professional and popular media. We all need to understand them.
Cause of DeathNumber of Percentage Deaths Heart Disease 616,067 25.4 Cancer 562,875 23.2 Stroke 135,952 5.6 Chronic Lower Respiratory 127,924 5.3 Accidents 123,706 5.1 Alzheimer’s 74,632 3.1 Diabetes 71,382 2.9 Influenza & Pneumonia 52,717 2.2 Other 658,457 27.2 Source: Centers for Disease Control and Prevention, as reported on http://www.cdc.gov/nchs/fastats/deaths.htm
A bar graph can be used to display and compare data. The scale should include all the data values and be easily divided into equal intervals.
Histogram is a bar graph that shows the frequency of data within equal intervals. There is no space in between the bars.
The table below shows the number of hours students watch TV in one week. Make a histogram of all the data. Number of hours of TV III6II1 IIII - IIII 7IIII2 III8 3 IIII9 IIII - I IIII - I4 IIII - III IIII - III5
Step 1 Make a frequency table of the data. Be sure to use equal intervals.Frequency Number of hours of TV 151-3 174-6 167-9 III6II1 IIII - IIII7IIII2 III8IIII - IIII3 IIII9 IIII - I4 IIII - III5
Step 2 Choose an appropriate scale and interval for the vertical axis. The greatest value on the scale should be at least as great as the greatest frequency. Step 3 Draw a bar for each interval. The height of the bar is the frequency for that interval. Bars must touch but not overlap. Label the axes and give the graph title