1957 - United Nations Statistics Division

time or the spacial variation observed must be interpreted
in this context.
Special attention should be directed to the possible
error introduced by exclusion of deaths of infants who
died before registration of birth. The effect of this procedure
may be judged from data for Guadeloupe and
Martinique, set forth in footnotes to Table 8.
Crude death rates measure the total decrease in the
population of an area due to death. Because they take no
cognizance of differences in the age-sex composition of
populations and since mortality is highest at the older
and younger ages, crude rates are not strictly comparable
from area to area. Nevertheless, they are useful in measuring
gross differences in the levels of mortality and as
a guide to areas where factors favouring excessive mortality
are operating.
Table 9
Statistics of infant mortality (deaths under I year of
age and infant-mortality rates) are given in Table 9 for
the period 1948-1956.
Coverage: These data relate to the present-in-area population
of the 167 geographic units for which recent
statistics on infant deaths were reported. Some of these
areas are represented by data for sub-national popUlation
groups, which are not nationally significant, but which
are included in order to provide an index to the availability
of infant-mortality statistics.
Rate computation: Computed in accordance with the conventional
method, infant mortality rates shown in this
table are the number of deaths under I year of age per
I 000 live births which occurred during the same time
period. This means that no adjustment was made to take
account of the fact that some of the infant deaths which
occur during a given year are deaths of infants who were
born during the preceding year. However, unless the numbers
of live births or infant deaths are changing rapidly,
the error involved is not important. 29
Limitations: Perhaps the most important and widespread
limitation on the comparability of infant mortality rates
is that resulting from compiling statistics of infant deaths
and live births by date of registration, irrespective of the
date of occurrence of the events. Where these procedures
obtain, a large increase, for whatever reason, in the number
of live births registered in anyone year may introduce
sizable errors into the infant mortality rates, especially
since deaths tend to be more promptly reported than
births.
If the delay in registration remains nearly constant and
is approximately the same for births and deaths, the rates
are not affected to any appreciable degree by this factor.
But if-as is the case in many countries-a large proportion
of the births are not registered until many years
after occurrence, then infant mortality rates obtained by
relating infant deaths for anyone year to births which
occurred over a period of years, have little validity.
Because of the importance of this factor, especially as it
relates to the live births which constitute the denominator
29 For a more detailed discussion of this problem, see "The Measurement
of Infant Mortality" by W. P. D. Logan. Population Bulletin
Of the United Nations. Department of Social Affairs, Population
Division. Document ST/SOA/Ser.N /3, October 1953, p. 30-67. (Sales
No. 1953'xm.8)
29
of the infant mortality rates, the statIstICS known to be
by year of registration are identified with a dagger (t).
Even on a "date-of-occurrence" basis, under-registration
of births and infant deaths also affects the infant
mortality rates unless the proportion registered is the same
for both components. In order that information on the
completeness of the data may be available, the code "C"
or "U", discussed in detail on p. 24 has been incorporated
into this table as a guide.
This code, which for lack of precise information is
essentially that shown in connexion with deaths at all
ages in Table 7, refers primarily to the completeness with
which deaths under one year are registered and reported.
As noted above, differences in levels of completeness between
the two components of the infant mortality rate,
i.e., the infant deaths and the live births, will bias the
rates upward or downward, the direction of bias depending
on which component is more fully registered.
Another factor which has a bearing on the completeness
of live-birth and infant-death registration is that concerned
with the statistical definitions of the events to be
reported. As indicated in the discussion on p. 26, the
exclusion from both the live-birth and the death register
of live-born infants who die before 24 hours of age or
before registration of birth, may distort the statistics to
some extent, tending to give the rates a downward bias.
Failure to register as a live birth each infant death which
occurs during the first few weeks of life may also be a factor
in the lack of comparability among infant mortality rates,
but the effect, if any, would be toward an upward bias.
Table 10
Distributions of deaths by age and sex are set forth in
Table 10 for the period beginning 1948. These distributions
may be used with those for 1936-1947 shown in the
1951 Demographic Yearbook to provide a 20-year coverage
of mortality statistics by age and sex. They represent
the latest information, including revisions and corrections,
available in the Statistical Office as of 1 November
1957.
"Age", as in other tables showing this characteristic, is
assumed to be expressed in completed years of life. The
age classification used is under 1 year, 1-4 years, 5-year
categories ending with 80-84, a residual group of 85 and
over, and "unknown". For statistics which do not conform
to this classification, supplementary revised boxheads
are run in, and/or the consolidation of age groups
with common class limits is indicated by horizontal bars
through the columns.
Coverage: Data are shown for 146 areas. Every area reporting
deaths classified as described above is included,
irrespective of the number reported for the year. Moreover,
data for sub-national coverage (geographic or
ethnic) are included in this table, distinguished from
national data by the use of smaller-type face. Thus, the
table may serve to indicate the countries which tabulate
deaths by age and sex.
Limitations: Data in this table are subject to the limitations
implied by the code of "completeness", which was described
in connexion with vital statistics in general p. 24)
and which appears on Table 7. Comparability may also
be affected to some degree by differences in the basis of