Question

1. A cohort study was conducted to study an E. coli 0157:H7 outbreak that occurred at an Epidemiology picnic. I.R. Macho cooked 175 hamburgers and 125 people got sick from eating his hamburgers. R.M. Cooke cooked 145 hamburgers and 128 people did not get sick from eating his hamburgers.   

1. Organize the data in a table that will be used to determine relative risk for the two different cooks, I.R. Macho and R.M. Cooke. Label the table columns and rows. The shaded area represents the main portion of the 2 X 2 table.

Exposure:	Outcome:		Total
	Yes	No
Total

2. Calculate the relative risk for those eating hamburger patties cooked by I.R.Macho as compared to R.M. Cooke.

3. Explain your answer to (B) above in narrative form.

Answer 1

Solution:

a)

Exposure: E. coli 0157:H7 outbreak	Outcome:		Total
	Yes	No
Yes	125	50	175
No	17	128	145
Total	142	178	320

b.relative risk for those eating hamburger patties cooked by I.R.Macho as compared to R.M. Cooke.

Group 1 risk(I.R.Macho): 125/175=0.71

Group 2 risk(R.M. Cooke):17/145=0.12

Relative risk 1(I.R.Macho): 0.71/0.12=6.09

Relative risk 2(R.M. Cooke):0.12/0.71=0.16

c. Relative risk for those eating hamburger patties cooked by I.R.Macho is 6.09 which is greater than 1.as compared to R.M. Cooke which is 0.16<1. Here we can say that risk associated eating hamburger cooked by I.R.Macho is greater than compared to eating hamburger cooked by R.M. Cooke.