Cole Nussbaumer Knaflic, author of Storytelling with Data, ran a design competition last month on slopegraphs, which is a fancy term for a line graph focusing on change over time. This seemed like a good opportunity to rethink how we see PISA (Programme on International Student Assessment) data.
Since 2010, Andreas Schleicher of the OECD has been briefing American policymakers and education leaders on PISA scores. The news on our 15-year-olds tends to stay the same—we do much worse than about three dozen countries and are about average in science and reading. We have begun to tune out the news, which is a shame since many of the best performing nations have pulled further ahead over time.
There are a variety of reasons we have done this, but the way the data is presented may be a contributing factor. Business Insider’s December 2016 story included a typical scoreboard:
The problem with this data view is we don’t see how the groups change over time. Presenting the data in a slopegraph might help.
Using color helps focus our attention. Students in Singapore, shown in purple, began in 2009 about a quarter of a school year ahead of the U.S. in math, and they are now two and a half years ahead. Students in Canada, shown in black, have seen scores decline but they are still more than a full year ahead of the U.S.
We needn’t include all 65 cities and countries that participate in PISA. Israel is notable because its’ students began a full year behind the U.S. and it has pulled even. Seeing the data in a fresh way doesn’t guarantee that policymakers and the public will act any more urgently, but it certainly can’t hurt.