Most alpine skiers and snowboarders do not use helmets. do helmets reduce the risk of head injuries? a study in norway compared skiers and snowboarders who suffered head injuries with a control group who were not injured. of 578 injured subjects, 96 had worn a helmet. of the 2992 in the control group, 656 wore helmets. state: is helmet use less common among skiers and snowboarders who have head injuries? follow the four‑step process to answer the questions about this study. (note that this is an observational study that compares injured and uninjured subjects. an experiment that assigned subjects to helmet and no‑helmet groups would be more convincing.)