Graphs are a fast and efficient way to convey information but they are often easily misinterpreted.

Exponential growth bias is one of the biggest ways in which we misinterpret graphs. we consistently underestimate our extrapolations when we’re asked to analyze data based on graphs showing growth that accelerates over time (as opposed to data showing linear growth).

Lorenzo Ciccione is a researcher who is devoted to studying how people extract meaning from graphs and plots. The inundation of data from the COVID pandemic offered a unique opportunity to explore what, if any, kinds of charts can help people make accurate sense of growing COVID cases. I recently heard him talk about his research in a conversation with Meriam Good, who is the president and CEO of Mind Science (Lorenzo won research funding through Mind Science's BrainStorm Neuroscience Pitch Competition.)

Simplicity is key

What Ciccione found is that people were able to more accurately predict COVID case numbers two weeks into the future when they were presented with simplified graphs showing the trend lines of exponential growth. When they were presented with “noisy” graphs, those spiky ones showing daily case numbers with all of its daily peaks and plummets, predictions were more likely to underestimate the growth.

Interactivity improves performance

Ciccione said that predictions were even more accurate when people were asked to demonstrate their knowledge in different ways than merely telling them a number. Specifically predictions were more accurate when people have the opportunity to actually point and click on a part of the exponential growth graphs. This kind of “active learning” is supported by decades of research in the cognitive sciences.

Are graphs always necessary?

For the purposes of science, public health, or mathematics it makes sense to use graphs and plots. But all of the perils that Ciccione highlights in his research made me wonder if charts aren’t really in the best interest of clarity and audience learning. in many cases it may be worth asking if using a chart or graph is the even necessary? If not, what other simple visual could be used to convey what you want to say?