Sarah Kliff and Aatish Bhatia for NYT’s The Upshot look at the uncertainty of prenatal tests for rare conditions. For some tests, the results are more often wrong than they are right, which causes issues when expecting parents don’t know that.

Along with square pie charts, the piece goes into more detail with unit charts to explain what the percentages mean from a counts point of view. So if a reader doesn’t quite know what a false positive is before reading, they will have a better idea after.

Tags: prenatal, testing, uncertainty, Upshot