What makes you trust a map? What does a chart need to show for you to believe the story that it’s trying to tell you? Why does an author include a graph of one set of data but not others in an article?
These questions are the beginning of being ‘data literate,’ which means you know how to read charts, graphs, and maps and you also consider whether the information they show is reliable and trustworthy.
Data illustrations like graphs and charts are telling stories. For example, the graph below from Pacomartin via Wikimedia Commons shows trends in spending on downtown gaming activity in Las Vegas versus non-gaming activity.
You can use the Four Moves to read and evaluate this graph.
Check for previous work. Data stories have storytellers. When I look at this graph, it looks like frankamartin is the one who made it. Who is that person? Have they done other trustworthy work?
Go upstream to the source. When I go to the Wikimedia site it came from, I see a note that the data came from “Nevada Gaming Comission Data.” Is that true? Maybe, although they misspelled the Commission’s name… Does the Commission publish similar data? A quick internet search might tell me.
Read laterally. From this data story, it looks like something drastic happened in July 2005 that make revenue jump up $10 million dollars in non-gaming areas. Did other people see this happen, also? There might be news stories covering this big event that a quick search could uncover. If there aren’t, maybe this graph isn’t very trustworthy.
Circle back. What is the story here? What is frankamartin trying to show with the data? Why did they use ‘monthly average’ for the red line and ‘moving 1 year average’ — are those two things comparable, or are they completely different?
Here is a 2 minute video example of using the moves to evaluate data.