Ninety-three percent of Allegheny County residents report wearing masks — which is somewhat reassuring — according to Carnegie Mellon University’s COVIDcast website. In Butler County, 87 percent of residents report using a mask all or most of the time in public, as does 86.75 percent of the population in Westmoreland County.

The university’s Delphi Research Group has been collecting real-time data on self-reported Covid symptoms across the country since April, through a survey conducted daily to Facebook users. It’s a way to provide county-level data about the Covid pandemic that’s not available anywhere else — and to help determine where case numbers could spike next.

Data is available for public perusal and updated every day on the COVIDcast website. It’s shared in more detail with health researchers, to help develop forecasts of localized Covid caseloads.

They’ve since expanded the survey to include questions about how people are responding to public health recommendations, like mask usage. Other questions include whether people are testing positive and who is getting tested.

“Some of these topics were partially addressed by the original survey, but we knew that as the pandemic changed and public health priorities adapted, our survey had to change, too,” says Alex Reinhart, assistant teaching professor in CMU’s Department of Statistics and Data Science and a member of the Delphi group.

More than a million U.S. residents have responded since the expanded survey was launched in September.

As part of its Data for Good campaign, Facebook sends the surveys to a number of its users every day. CMU and the University of Maryland manage the findings, which Facebook does not keep.

In Pennsylvania, 87.72% of users responded that they use a mask all or most of the time. Usage is particularly high in New England (94% in Massachusetts), which was hit hard by the earliest wave of Covid. It’s lowest in North and South Dakota, around 70%, states that are currently seeing spikes in the virus’ transmission.

“Our survey doesn’t replace official public health reporting on Covid testing and case counts, but it can provide insights not available any other way,” Reinhart said. “By providing these signals to the public, we hope to give researchers, public health officials and journalists the information they need to form a more complete picture of the pandemic.”

The Delphi Research Group has been working on forecasting nationwide influenza outbreaks for years. It was designated last year by the Centers for Disease Control and Prevention (CDC) as one of two National Centers of Excellence for Influenza Forecasting. It’s adapting its flu forecasting abilities to COVID-19 at the CDC’s request.