Standardisation (cont.)
Choosing the Standard Population
The standard population used can be any population: it could even be one of the populations we are studying. It is important to specify which standard population was used, because the choice of standard population can affect the results of the comparison.
Using the previous example, instead of using the imaginary standard population, we'll use the Ecuadorian population as the standard.
Exercise
In the table below, calculate the missing values to the nearest whole number; then find the age-adjusted mortality rate to one decimal place.
| Age (years) | Mortality Rate for Sweden (per 1000) | Standard Population | Expected No. of deaths |
|---|---|---|---|
| 0-29 | 0.45 | 7,498,000 | 3374 |
| 30-59 | 2.4 | 3,219,000 | 7725 |
| 60+ | 42.4 | 742,000 | |
| Total | 11,459,000 |
Yes, the expected number of deaths is 42.4 x 742 = 31461.
No, you should have multiplied the mortality rate for this age group (42.4) by the standard population in the same group in thousands (742), to give an expected number of deaths of 31461.
That's right. Now calculate the age-adjusted mortality rate.
No, the total should be 42560. Did you get the correct answer for the expected number of deaths in the 60+ age group?
Age-adjusted mortality rate for Sweden
| = |
?
|
= | |
| 11,459,000 |
Yes, that's correct, the age-adjusted mortality rate for Sweden, using Ecuador as the standard population, is 3.7 per 1000 person-years.
No, that's not right. Check your workings; if you have got the previous two values correct, you should have an age-adjusted mortality rate of:
42 560/11 459 000 = 3.7 per 1000.
42 560/11 459 000 = 3.7 per 1000.