5 questions to ask about charts

More and more, charts and graphs are being used in the news and in reports. But, there’s more to reading a chart and understanding what’s going on that just looking at the bars or lines.

Here’s 5 questions you can ask when you see a chart or graph to help ensure you understand what’s going on.

1. What is this chart or data about?

Read the title of the chart, the axis labels, and any extra information (sometimes called metadata). If there are terms you don’t understand, stop and look them up. Make sure you understand how the data is measured. Is it a median? A mean? An index? A rate?

Check how the data was collected. Was it a survey or a census or administrative data or something else? Check when the data was collected and what time period it covers.

2. What does the data show?

Describe what you see in the data in a couple of sentences. For example “This chart shows a generally increasing trend line going from around 1.5 million people in 1937 to nearly 5 million people in 2018.”

3. How does this compare with other data?

Once you understand what the data on the chart shows, take a step back. Think about what this data may compare to. Can you compare it to another country over the same time period? Perhaps you can look at previous years of the same data. Maybe you can compare it to another group in the same dataset.

You want to understand whether what is happening in the chart you are reading is expected and similar to other groups or if it’s something out of the ordinary.

4. What could be happening in the real world to create these figures?

There are so many things that can cause changes or unexpected numbers in data. Sometimes it can be statistical things like a change in how something is measured. Sometimes it’s because of the way something is measured or collected. Sometimes, it can be a policy change or a public campaign that raises awareness and changes behaviour. Sometimes it can be a commercial decision that impacts things like prices. Sometimes it can be a natural event like a drought or a flood that affects growth and supply.

Researching and understand what was happening during the collection of the data can help ensure you don’t jump to conclusions.

5. Who could this be relevant for, and why?

Different datasets can help different people in different ways. For example, a chart about the estimated population growth in different parts of New Zealand might help a construction company decide where to build. Information about the changes in prices of fruit and vegetables might help people decide what to buy each month to get the best deal. This might also be helpful for budgeting services.