Interpreting categorical data

You see data every day, even if you do not know the word yet. Data is just information that has been collected. When your class votes on the best game to play, that vote is data. When you count how many sunny days happened this week, that is data too.

One easy way to collect data is to ask everyone in your class a question, like, what is your favorite fruit? Each answer goes into a group, like apples, bananas, or grapes. Then you count how many answers are in each group.

After you collect the data, you can read it to learn things. You can answer how many students picked grapes. You can add up all the groups to find how many students answered in total. You can even compare two groups and say how many more picked bananas than apples.

Data can come from many places, like the news, a book, or a science project. Once you know how to read it, data can tell you a story about the world around you.

A pie chart is a circle that shows data. The circle is cut into slices, and each slice stands for one group, like one favorite color or one kind of pet.

Here is how to read one. First, look at the labels. Each label tells you what group its slice stands for. Next, look at the size of each slice. A bigger slice means more things are in that group. A smaller slice means fewer things.

For example, imagine a pie chart of your class favorite fruits. Half the circle is apples, so most of the class picked apples. A small slice is grapes, so only a few picked grapes. By just looking at the slices, you can tell which group is the biggest and which is the smallest.

Pie charts work best when there are only a few groups, about six or fewer. With too many slices, the chart gets hard to read. When you make your own pie chart, start by counting how many are in each group, then give each group a slice that matches its size.

Scientists who study weather watch the sky and collect data. They count the clouds they see and write the numbers down. Then they turn those numbers into graphs so the data is easy to read.

A graph can show how many cloudy days and how many sunny days happened in a month. By reading the bars, the scientist can answer questions. How many days were cloudy? How many were sunny? Which kind of day happened more often, and by how many?

You can do the same thing. Count something around you, like how many birds visit your window each day. Make a graph with one bar for each day. Then read your own graph. The tallest bar tells you which day had the most birds. Comparing two bars tells you how many more birds came on one day than another. Data you collect yourself can tell you surprising things.