1957 - United Nations Statistics Division

Table 4
Table 4 shows the latest post-censal estimates of population
classified by age and sex, together with the results
of censuses of population which were taken in 1945-1957
but which were not available in time to be included in
the 1955 or 1956 Demographic Yearbook. It will be recalled
that Table 10 of the 1955 Yearbook showed all
census returns available at that time from enumerations
carried out between 1945 and 1954. The 1956 Yearbook
supplemented that comprehensive coverage with new or
revised censuses and latest estimates. Table 4 in this issue
continues this practice with censuses taken through 1957.
The census data shown are for both national and subnational
segments, depending on the coverage of the respective
enumerations. The estimates are assumed to be
constructed on the basis of the census returns, using
statistics of births, deaths, immigrants, and emigrants to
adjust the base population to a current date. In general,
estimates relate to the mid-year but, in a few cases, the
mean population, calculated from two end-year estimates,
is given. These estimates are so identified in this
table.
The age classification shown for censuses and estimates
is based, unless otherwise indicated, on age at last birthday.l4
It includes 20 categories as follows: under 1 year;
1-4,5-9, continuing in 5-year groups to 84; a residual category
of 85 and over; and unknown. This classification
represents a slight modification of that recommended by
the United Nations Population Commission,15 which suggested
single-year tabulations from I through 4 and 5-year
groups to the end of life.
Unless otherwise noted, the data relate to the modified
present-in-area population of geographic areas within
present territorial boundaries, as described on p. 15. If
the "modification" has involved large numbers of persons,
a special note is also appended for clarity even
though the resulting estimate is the standard for the table.
Coverage: Table 4 includes one or more age-sex distributions
for 61 geographic units, comprising a total of 70
separate arrays, of which 28 relate to a census count and
40 to postal-censal estimates.
Availability was not the sole criterion used in determining
the scope of Table 4. A number of available agesex
distributions of population were deliberately excluded
on the basis of their construction. To be included in
this table, an estimate must have been constructed by
the natural increase method, supplemented of course by
migration statistics if available. Distributions which result
when the estimated total population is distributed by
age and sex according to percentages in each age-sex
group at the time of the census are aot acceptable. Such
distributions are on file for Bolivia, Ceuta, Colombia,
Dominican Republic, Egypt, Melilla, Mexico, Philippines,
Spain, and Thailand.
Limitations: Comparability of population data classified by
age and sex, is limited in the first place by variations in
the definition of total population which has been discussed
in detail on p. 15, and by the completeness of
the original enumeration, also discussed above. Both
of these factors are more important in relation to certain
14 For a discussion of this factor, see the 1956 Demographic Yearbook,
p. 26.
15 Report of the Population Commission (Fourth Session), document
E/1313, p. 17.
22
age groups than to others. For example, underenumeration
is known to be more prevalent among young children
than at older ages; the composition of the "total" population
is primarily a function of the inclusion or exclusion
of certain groups who may be of selected ages, such as
members of the armed forces and so forth. Consideration
should be given to the implications of these basic limitations
in using the data.
In addition to the defects inherent in the basic census
data, estimates of population suffer also from lack of
comparability in quality. To evaluate this factor, reference
should be made to the "type-of-estimate" code described
on p. 16. The classification of 1956 estimates by
this code may be found in Table 1, and it may be assumed
that the code is generally applicable to other postcensal
estimates unless the post-censa1 period is excessively
long.
Further to these general qualifications are the special
problems of comparability which arise in relation to age
statistics in particular. Age-sex distributions of population
are known to suffer from certain deficiencies which
have their origin in underenumeration of infants and in
irregularities in age reporting. A discussion of these irregularities
together with a description of the procedures
for testing age accuracy and the results of its application
to single-year-of-age data are given on p. 17. Although
some of the irregularities in the age statistics tend to be
obscured or eliminated when data are tabulated in 5-year
age groups, precision still continues to be affected, though
the degree of distortion is not always readily seen. The
classification of age distribution by Whipple's Index
given in the 1955 and 1956 Demographic Yearbooks will
thus continue to serve as a guide to the evaluation of
age-sex accuracy in Table 4.
Another limitation on comparability is found in the
basis for the age classification employed by the various
countries. Whenever it was known that the classification
was based on other than age at last birthday, the data are
so noted in the tables and allowance should be made for
this factor in using the data.
Deviations from the standard age classification of the
ta ble are shown by bracketing and footnotes. Although
precise international comparability of specific age groups
is often lacking, the data are nevertheless included because
of their basic value for the area concerned. This is
particularly true for African areas; since statistics for
these territories have not been generally available until
recent years, the results of sample censuses and others
employing unconventional methodology are included because
of the scarcity of information for this continent.
In connexion with the age classification, it should be
noted that zero frequency reported in the unknown-age
category is not always an indication of perfect age reporting-,
but may be an indication that ages have been assigned
before tabulation began. The method of age allocation
!s not always known and hence it is noted infrequently
III the tables, but the possibility of its having occurred
should not be overlooked.
Table 5
Table 5 presents the latest estimate or enumeration of
population in the national capital of each country irrespective
of size, together with that in cities having at
least 100,000 inhabitants.