# 9 – Descriptive Statistics

• The crowd cheers as the first cyclists came into view at the finish line of the 25 kilometer charity bike ride. What is the fastest race time? When did the largest group of riders come through? How spread out were the riders? Was there a straggler? When did the last rider finish?
• By collecting and organizing data—like the race times—you can answer questions like these. Descriptive statistics allow you to describe and summarize the data in a clear and meaningful way.
• Descriptive statistics help you visualize the data and see the patterns that emerge.
• What was the average time it took to finish the race? If you had more data about the individual riders, you might compare sets of data by asking questions such as “Does the amount of time spent training correlate to the race time?”
• In this unit you’ll explore the two basic methods of descriptive statistics—graphical and numeric. You’ll use a variety of tables, graphs, and plots to visualize what the data is showing.
• You’ll summarize these patterns by computing statistics that describe the distribution, central tendency, and spread of the data.
• You’ll even begin to look at relationships between data sets.