First look at the DIRECTION.......
Cross-multiply AxD / BxC...
THIS IS CALLED THE "ODDS RATIO"
ODDS RATIO of 5.40 is NOT 1.0, so we HAVE A RELATIONSHIP (ASSOCIATION) BETWEEN EXPOSURE AND ILLNESS! (1.0 means NO RELATIONSHIP)
So... the EXP group was 0.25 times as likely to be ill as the Non-EXP group... OR if you prefer ... The Non-EXP group was 4 times as likely to be ill as the EXP group
INCIDENCE RATES are the (number of cases of illness)
(Total # of people)
Here we have Incidence rates for the EXP group and also for the Non-EXP group
The outcome indicates the deaths from lung cancer
PER YEAR for each exposure group. If we place the
new deaths for lung cancer for one year over the
group population, we have the true incidence rates
for both groups
The interpretation is similar to the interpretation for the odds ratio.
In this study, we can observe a 13 times increased risk for developing
lung cancer among smokers compared to non-smokers. This additional
risk of lung cancer due to smoking has now been observed in more than
60 fully-accredited studies. All studies