Step 1:  total population in Qatar is 173,000 from which >15 years 101,000 (53%)

Step 2:  prevalence of CHD is 13% according to family health survey

Step 3:  expected number = 13 X 101/1000 =13130

Step 4:  those who access the service 8909 (68%) from 13130 (100%) CHD population according to hospital records

Step 5:  unmet needs = 13130 (100%) - 8909 (68%) = 4221 (32%)

Step 6:  segment your population like obese people, smoking, hypertensive ………..