The study reported 45 injuries to the upper extremity on a dry field consisting of artificial turf over the course of 10,112 games. What procedure can be used to assess whether the risk of injury is different on artificial turf versus natural grass? 

Sports Medicine

Injuries are common in football and may be related to a number of factors, including the type of playing surface, the number of years of playing experience, and whether any previous injury exists. A study of factors affecting injury among Canadian football players was recently reported [11].

The rate of injury to the upper extremity (that is, shoulder to hand) on a dry field consisting of natural grass was 2.73 injuries per 1000 games. Assume this rate is known without error.