Course Certification & GPS Discrepancies
The Rite Aid Cleveland Marathon and 10K courses are certified each year according to USATF standards, using a bike equipped with a calibrated measuring wheel and following the shortest possible route (tangents). Additional distance discrepancies are caused by the actual route run on the course and the accuracy of individual GPS units being used by runners.
The Rite Aid Cleveland Half Marathon course has never been certified since its inception in 2005, nor has it been advertised as such. However, it is measured repeatedly to be as close to 13.1 as possible.
Click here to read an article on course certification and the accuracy of GPS measurements.