Introductory Biostatistics

for each age group of each of the two populations being compared. For

example, for age group 0–4, the U.S. population for 1970 was 84,416 (per

million); therefore, we have:

(a) Alaska rate¼405.0 per 100,000. The expected number of deaths is

ð 84 ; 416 Þð 405 : 0 Þ

100 ; 000

¼ 341 : 9

F 342

(Fmeans ‘‘almost equal to’’).

(b) Florida rate¼375.3 per 100,000. The expected number of deaths is

ð 84 ; 416 Þð 375 : 3 Þ

100 ; 000

¼ 316 : 8

F 317

which is lower than the expected number of deaths for Alaska

obtained for the same age group.

3. Obtain the total number of deaths expected.


4. The age-adjusted death rate is

adjusted rate¼

total number of deaths expected

total standard population

 100 ; 000

The calculations are detailed in Table 1.8.
The age-adjusted death rate per 100,000 population for Alaska is 788.6 and
for Florida is 770.6. These age-adjusted rates are much closer than as shown by
the crude rates, and the adjusted rate for Florida islower. It is important to
keep in mind that any population could be chosen as ‘‘standard,’’ and because

TABLE 1.8

Alaska Florida

Age
Group

1970 U.S.

Standard

Million

Age-

Specific

Rate

Expected

Deaths

Age-

Specific

Rate

Expected
Deaths
0–4 84,416 405.0 342 375.3 317
5–19 294,353 83.6 246 60.3 177
20–44 316,744 261.0 827 190.5 603
45–64 205,745 777.6 1600 1101.5 2266
65 þ 98,742 4933.3 4871 4397.9 4343

Total 1,000,000 7886 7706

RATES 17