Higher concentrations of streetlights do not guarantee fewer nonviolent crimes in Houston neighburhoods, according to a new report from Rice University’s Kinder Institute for Urban Research.

“What Happens in the Shadows: Streetlights and How They Relate to Crime” examines how the city of Houston’s 173,000 streetlights impact crime rates. The report comes as Houston is converting its streetlights to LED bulbs. This activity prompted the Kinder Institute to examine streetlight density across the city.

The researchers compared 2015 crime rates of areas of the city with both high and low density of streetlights and looked for patterns to determine if there was a relationship between these factors. Streetlight density was measured by dividing the number of streetlights in a census block by the length of road miles within the block. It ranged from a low of less than one streetlight per mile of road to a high of 47 streetlights. The city of Houston’s average streetlight density is about 15 streetlights per mile of roadway.

The report revealed that crimes occur throughout the city in areas with both high and low concentrations of streetlights. However, the researchers found no direct correlation between higher densities of lights (more than 15 streetlights per mile of roadway) and lower rates of nonviolent crimes.