A study was conducted in men aged 40-70 in order to determine whether exercising for 2 or more hours per week decreases the likelihood of a heart attack. The cases were 1,000 men who had recently had a heart attack; of these, 236 reported that they had regularly exercised for two or more hours per week prior to their heart attack. 1,000 controls were also selected for the study; of these, 379 reported that they exercised regularly. Calculate the magnitude of the association between regular exercise and heart attack. What does your calculation suggest