President Joe Biden likes to recall a conversation he had with Gianna Floyd, George Floyd’s daughter, at Floyd’s funeral last summer. “Daddy changed the world,” she told Biden. If the first step to changing the world is changing people’s minds, Floyd’s murder one year ago did that—though just how much, and with what long-term effects, remain unclear.

To understand any data set, you have to understand the way its information is compiled. That’s especially true for a patchwork data set such as the one composed of U.S. COVID-19 data, which is the product of 56 smaller systems belonging to each state and territory in the country.In our year of working with COVID-19 data, we harnessed our attention on these systems and found that much of the information they produced reflected their individual structures.

The mysterious flying objects showed up in Washington, D.C., on a hot, humid night in the summer of 1952. The air-traffic controllers at the airport saw them first, and then so did the operators at nearby Air Force bases—seven unexplained blips on their radar screens. A commercial pilot in the vicinity reported seeing bright lights in the darkness. The Air Force dispatched fighter jets but found nothing. A week later, it happened again. More blips. More jets.