A consumer group is accusing the Massachusetts Bay Transportation Authority of misleading its riders about how reliable its service is.
Last year, the MBTA started the Performance Dashboard website for riders that tracks the subway's reliability.
Over the last month, the website says the MBTA's dependability score is 88 percent.
But according to the Boston Globe, the Massachusetts Public Interest Research Group is releasing a report Thursday that says the MBTA's method of tracking reliability is flawed.
MBTA officials told the Globe they look at how long it takes a passenger to catch a train once they enter a station since subways do not have fixed arrival and departure times like the commuter rail.
MassPirg says that inflates the MBTA's reliability numbers because some passengers are getting on subways that are running late.
The MBTA says it's always working to improve on-time performance for riders. New subways planned for the red and orange lines are expected to help do that.
A statement released by the MBTA on Thursday says that Performance Dashboard continues to be a model for transit systems around the country.
"To present customers with the most useful information, the T’s reliability measures compare service performance to the schedules provided to the public. The Dashboard is evolving, and MBTA staff is open to ideas that can improve its performance measures given the T’s best available data sources. The MBTA also collects data through passenger surveys to help the T better understand what drives customer satisfaction and how customers rate service. To enhance the subway reliability measure, the T is working with UMass Amherst and MIT to make improvements."