Answer Happy

Researchers sought to determine the incidence of type 2 diabetes
in women aged 60–75 years. The study participants were followed for
three years with yearly assessments to determine whether they met
the diagnostic criteria to be cases. At baseline, there were 2000
women and none of these had detectable type 2 diabetes. After one
year, none had a diagnosis of the disease, and 100 had been lost to
follow-up. After two years, 8 had a diagnosis of the disease and
another 92 had been lost to follow-up. After three years, another
12 had a diagnosis of the disease, and 88 had been lost to
follow-up.
Calculate the incidence rate in person-years of type 2 diabetes
in this group over the entire period of observation. You
should assume that persons with a new diagnosis were disease-free
for half the year, and those lost to follow-up were at risk for
half the year.