demographic yearbook annuaire demographique 1951

mortality rates for 119 areas for the period 1930 to 1950.
The rate is the number of deaths under 1 year of age reported
for each calendar year per 1,000 live births reported for
the same year. Infant mortality rates are computed with
reference to live births instead of to the midyear population
under 1 year of age because the number of births is a
better measure of the population that is exposed to the
possibility of dying during a given year at ages of less
than 1 year.
In the computation of the infant mortality rates shown, no
adjustment was made to take account of the fact that some
of the deaths during a given year are deaths of infants who
were born during the preceding year. The rates are based
on the births which occurred in the same calendar year as
the deaths. However, unless birth numbers or infant death
rates are changing rapidly, the error involved is not
important.
In countries where statistics refer to events registered,
irrespective of date of occurrence and where registration
procedures are irregular, drastic fluctuations in the number
of births registered may introduce sizable errors into the
infant mortality rates, especially if deaths tend to be more
promptly reported than births. If the lag 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.
Underregistration of births and infant deaths also affects
the rates unless the proportion registered is the same for
both components. Differences in the proportion registered
will bias the rates upward or downward, the direction of
the bias depending on which component is more fully registered.
The omission of equal numbers of births and deaths,
which occurs when deaths of infants whose birth was
unregistered are excluded from the death statistics, gives
the rates a downward bias.
Statistics of infant deaths classified by subdivisions of the
first year of life and by sex are presented in table 20 (69
areas) and table 21 (68 areas) for the period 1936 to 1950.
These data are useful in the analysis of mortality because
the probability of dying changes markedly during the first
year of life, being considerably higher at the beginning of
the year and decreasing rapidly thereafter.
Table 20 gives annual numbers for each sex but not for
the two sexes combined. Deaths of unstated sex are therefore
excluded and the implied totals in some cases disagree slightly
with those shown in table 18. As for the previous tables,
discrepancies are noted unless they are very small.
Methods of reckoning the age of infants at the time of
death vary. This is an important consideration with respect
to age intervals up to one week. In general, the age at death
is determined on the basis of the time elapsed after birth
(hours, minutes, days, as appropriate) and is expressed in
completed units of time. In some cases, however, the age is
expressed to the nearest day or is based on calendar days,
the calendar day of birth being counted as the first day of
life and infants dying the day after birth being classified as
1 day of age even though they may have died less than 24
hours after birth. Age classifications known to be expressed
in other than completed units of time, reckoned from the
exact time of birth, are noted in the table. This factor is
disregarded for age intervals of one month or over.
Table 21 gives annual rates for each sex and for the two
sexes combined. The rate is the number of deaths of the
given age and sex per 1,000 live births of the same sex.
Thus, the base of each age-specific rate is the same as that
of the rate for all deaths under 1 of the same sex. The rates
are therefore additive by age but not by sex. The total
rate (for both sexes combined) shown in the first column
of the table is the conventional infant mortality rate that
appears also in table 19, infant deaths for which the sex or
the exact age is unstated being included in the computation.
Table 22 and table 23 present statistics of causes of death.
Table 22 gives for 51 areas the number of deaths from each
cause and corresponding cause-specific rate (deaths from
each cause per 100,000 persons in the total population) for
the years 1947 to 1949. Deaths classified by cause, age and
sex for 27 areas are given for a recent year (1947, 1948 or
1949) in table 23. In both tables the classification by cause
is according to the abridged list of the Fifth (1938) Revision
of the International List of Causes of Death. A discussion
of cause-of-death statistics and of the problems involved in
their interpretation is given in Chapter II.
In the compilation of these tables available data for some
of the areas have not been included. Where the number of
deaths was less than 1,000, in the case of table 22, or 5,000,
in the case of table 23, the data have been omitted because
of the smallness of the numbers for individual causes and
age groups. Even among the data presented in the tabies,
some of the frequencies are very small and the accompanying
rates are of little value.
Where the data shown are limited in their coverage the
pattern of the cause distribution should not be taken as
indicative of that for the area as a whole. Particular care
should be taken in interpreting data where a high proportion
of deaths is recorded as due to senility or to unknown,
ill-defined or unspecified causes. The relative magnitude of
this group for the areas appearing in table 22 is given in
Table 0 of Chapter II.
The age groups shown in table 23 are as follows: under
1 year, 1-4, 5-14, 15-24, 25-44, 45-64, 65 years and over.
Because of considerations of space, it was not possible to
show a more detailed age grouping, but the groups selected
correspond to the major stages of life from infancy to old
age and reflect the characteristic age distribution of particular
diseases. For example, certain communicable diseases
such as measles and whooping cough occur most
frequently in childhood and adolescence, but diseases of
the heart, intracranial lesions of vascular origin and cancer
are more frequent among the older population.
Since these data refer only to a very recent period of time,
they do not reveal trends but they do permit comparisons
for various parts of the world.
MARRIAGE AND DIVORCE STATISTICS
Table 24 and table 25 present statistics of marriages. Because
marriage is a legal process rather than a biological
fact such as birth or death, the problem of comparability
takes on a somewhat different aspect in relation to these
data. The statistics presented refer to formal marriages
officially recognized as such in the laws of the respective
countries. In some cases these include both civil and religious
marriages; in others only civil marriages or only
religious marriages. Consensual unions are excluded, except
as special measures for legalizing them may bring them into
the category of legal marriages. In some countries such
unions are as frequent as formal marriages and are accepted
as marriages in the local mores. Statistics for these countries
35