The findings have implications both for crime control efforts and for the heavy reliance on standardized tests, said Sharkey. They can also explain about half the achievement gap between blacks and whites on such tests, he reported in the Proceedings of the National Academy of Sciences. If a murder occurred in a child’s neighborhood — an area of roughly six to 10 square blocks as denoted by the U.S. Census — the children’s test scores fell by an average of half a standard deviation, Sharkey reported.
“When one takes into account the prevalence of homicide in the most violent neighborhoods in cities like Chicago, these results mean that some children spend about one week out of every month functioning at a low level as they navigate the home or school environment,” he said in a statement.
In general, black U.S. children score about one standard deviation lower on standardized tests than white children. This finding accounts for half that difference, Sharkey said.