00:01
So here we're given a figure that represents a population of 75, and we have a period of two years.
00:26
And then for part a, we want the point prevalence on january 1, 2010, so 1 -1 -2010, for a population of 100 people instead of 75.
00:57
Well, for my graph then, i see that on 1 -1 -2010, i have, let's see, 1, 2, 3, 4, 5 cases that started before then.
01:15
So that is the number of people who are currently 6, so that is 5, and that is out of my population of 75.
01:26
So i then have to multiply that fraction, 5 out of 75, by 100 to get the prevalence rate per 100, and that then is equal to 6 .67.
01:48
And then for part b, i want the period prevalence, so this was the point prevalence, the period prevalence, from 1 -1 -2010 to 1 -1 -2011 per 100 population.
02:26
So now i want to include anyone who was ill between january 1, 2010 through january 1, 2011, and i count 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 of these, so this one is going to be 10.
02:47
Our population at risk was 75 here, so that's the ratio in this population, and since i want this per 100 population, i multiply by 100, and that gives me 13 .3 per 100...