A prevalence survey conducted form January 1st through Decem

A prevalence survey conducted form January 1st through December 31st 2008 identified 5,000 cases of bi polar disorder in a city of 4 million persons. The incidence rate of bi polar disorder in this population is 8 psi 100,000 persons per year. What percent of the 5,000 curves were newly diagnosed in 2008? Be sure to show all of your work.

Solution

Since the incidence rate of bi polar disorder is 8 person per 100000 population per year,

So the incidence rate of bipolar disorder on 4 million population would be

= 8*40

= 320.

It means on an average, incidence rate of bipolar disorder would be 320 person per 4 million population.

Now it is observed that 5000 cases have been found within a year 2008. So the number of new cases would be

= 5000 - 320

= 4680

So, the percentage of newly diagnosed people having bipolar disorder are

4680*100/5000

= 93.6% .