In a mass screening 1,329 men aged 40-59 years were examined with regard to serum cholesterol and systolic blood pressure, and then followed over a 6-year period for the development of coronary heart disease (CHD). At the beginning of the period all were free from CHD.
Which measure of occurrence for CHD can be calculated?
NOTE: There can be more than one correct answer.

  Systolic Blood pressure (mm Hg)
< 147 147-166 ³167
(Serum cholesterol
mg/100 ml)
# Men#Men with CHD # Men #Men with CHD # Men #Men with CHD
< 220 431 10 93 3 49 7
220 - 259347 1974 649 6
³ 260 18519 57 11 44 11