Encyclopedia of Sociology

DEMOGRAPHIC METHODS

Age Pyramid of Mexico Age Pyramid of Norway

1990 1997

Percentage Percentage

Panel A Panel B

14 12 10 8 6 4 2 0 2 4 6 8 1012 14

0-4

5-9

10-14

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85-89

90 +

Males Females Males Females

12 10 8 6 4 2 0 2 4 6 8 101214

Figure 1

NOTE: Age pyramids for Mexico and Norway

Norway, 10.1, seven years later, in 1997. Knowing
nothing else about these two countries, we might
infer that the health of the Mexican population
was considerably superior to that of the Norwe-
gian population. However, once we standardize
the crude death rates of the two countries on a
common population age structure, we find just the
reverse is true.

To accomplish this standardization, instead of
applying the above equation to our data, we use
the following:

[nMxA. nPxs]

ASCDRA =

∑

ω-n

x= 0 ,n

∑

ω-n

x= 0 ,nn

Pxs

( 2 )

where ASCDRA is the age-standardized crude death
rate of country A, and nPxS is the number of indi-
viduals in the standardized population of that
same age group. Any age distribution may be
chosen as the standard, however, it is common
simply to use the average of the two proportionate

age distributions (i.e., each normalized to one in

order to account for unequal population sizes).

Table 1 gives the death rates and number of

persons for each country by five-year age groups

(zero through four, five through nine, and so on

through eighty and above). The first fact we glean

from the table is that the mortality rates of the

Norwegian population are substantially lower than

those of their Mexican counterparts at virtually all

ages. We see that nearly 40 percent of the Mexican

population is concentrated in the three age groups

having the lowest death rates (ages five through

nineteen). Only half that proportion of the Norwe-

gian population is found in the same age range. In

contrast, only 6 percent of the Mexican population

is above sixty years of age, an age range with which

its highest level of mortality is associated. At the

same time, about 20 percent of the Norwegian

population is sixty or older. Compared with the

Mexican crude death rate, then, the Norwegian

rate is disproportionately weighted toward the

relatively high age-specific death rates that exist in

the older ages.