Question

Epidemiology: Calculate the answers using the table.

		Sick	Well	Total
	Yes	82	5	87
Ate the Salomon	No	4	18	22
	Total	86	23	109

Find the incidence proportion:

Find the Attack rate:

Find the food-specific attack rate:

Find the risk ratio:

Answer 1

a. Incidence proportion:

Number of people effected (sick)/Total number of people

Number of people effected (sick) = 86

Total number of people = 109

Therefore incidence proportion = 86/109 = 0.78

b. Attack rate

Attack rate = Number of new cases of disease during specified time interval.

Attack rate = Number of people effected (sick)/Total number of people

            = (86/109)*100 = 78.89%

c. Food specific attack rate

Food specific attack rate = Number of persons sick after ate salomom/Total number of persons ate salomon = (82/87) × 100 = 94.25%

d. Risk Ratio

Risk Ratio = cumulative Incidence in exposed group/cumulative incidence in unexposed group

		Sick	Well	Total	cumulative Incidence (Number of people affected/total number of people)
	Yes	82	5	87	82/87*100 = 94.2%
Ate the Salomon	No	4	18	22	4/22*100 = 18.2%
	Total	86	23	109

Risk Ratio = 94.2/18.2 = 5.17