demographic yearbook annuaire demographique 1951
demographic yearbook annuaire demographique 1951
demographic yearbook annuaire demographique 1951
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The second part, represented by a numeral, indicates the<br />
method utilized for adjusting the basic data for a current<br />
date and, where the method is the "balancing equation"<br />
• (i.e., adjustment by means of statistics of births, deaths and<br />
migration), the general quality of the data used in the<br />
adjustment. Where the basic data on population size are<br />
supplied each year, as is generally the case with a continuous<br />
population register, no adjustment of the basic data is<br />
required, and the second part of the code is shown as "0".<br />
The full code and its interpretation are given in the note at<br />
the end of table 1.<br />
The general arrangement of letters and numerals follows a<br />
descending scale of reliability. The code "RO" indicates<br />
that the estimates were obtained directly from a continuous<br />
population register and that they may be regarded as of the<br />
first order of reliability. For present purposes a continuous<br />
population register is defined as a registration system which<br />
maintains an individual record for each person in the population,<br />
a record being added for each birth, a record being<br />
removed for each death, and provision being made for the<br />
transfer of records with changes of residence. In so far as a<br />
figure for the total population can be obtained directly from<br />
such records each year, the accuracy of estimates so obtained<br />
is relatively independent of the periodicity or recency<br />
of population censuses or of the compilation of birth and<br />
death statistics from another source. Generally speaking,<br />
continuous registers lead to estimates which are superior to<br />
those derived from censuses, whereas other non-censal<br />
counting methods lead to less reliable estimates.<br />
Estimates based on census enumerations are coded "A",<br />
"B", "c" or "D", according to date and frequency, as<br />
specified in the note at the end of table 1. No qualitative<br />
distinction among censuses has been attempted, but it<br />
should be understood that not all censuses are ofcomparable<br />
accuracy.<br />
Estimates based on non-censal counting procedures are<br />
coded "E", regardless of their recency or frequency. This<br />
category covers a fairly wide range of types, including ration<br />
registrations, tax lists, hut counts, partial enumerations and<br />
group enumerations such as are made in a number of<br />
Mrican areas where the household, tribe or village serves<br />
as the unit for counting. The accuracy of these counts varies<br />
considerably, but as a group they may be regarded as yielding<br />
results inferior to those generally obtained by the census<br />
method of individual enumeration. In the case of annual<br />
counts (coded "EO") the yearly repetition of the operation<br />
is likely to lead to improved accuracy.<br />
Estimates based on conjectures or guesses as to population<br />
size made at some time in the past (i.e., before 1948) are<br />
coded "F". In some cases these "base estimates" are held<br />
constant; in others an assumed rate of increase is applied.<br />
Such estimates are of a highly dubious accuracy and should<br />
be regarded merely as rough indications of probable population<br />
size.<br />
The numerical part of the code distinguishes three types<br />
of adjustment procedure. The first type, adjustment on the<br />
basis of statistics of births, deaths and migration, is coded<br />
"1" if the data are held by official and other reliable sources<br />
to be substantially accurate, "2" if the components of natural<br />
increases are substantially adequate but the adjustment<br />
for migration either is not made or is based on inadequate<br />
information, "3" if the birth and death data are of unknown<br />
reliability and "4" if they are known to be deficient. In the<br />
case of "3" or "4" the quality of the migration data is<br />
disregarded.<br />
The second type, mathematical interpolation or extrapolation<br />
of two or more population counts (coded "5"),<br />
is, on the whole, an inferior method as compared with the<br />
first type, except in cases where vital statistics or migration<br />
data are deficient. Interpolations are likely to be more<br />
reliable than extrapolations; interpolations for a short intercensal<br />
period are more reliable than those for a long intercensal<br />
period. In specific cases the type of curve selected<br />
may have some bearing on the accuracy of the estimates<br />
obtained, but an evaluation of these has not been attempted.<br />
The third type of adjustment, an assumed rate of increase<br />
not derived by mathematical interpolation or extrapolation,<br />
is coded "6". Estimates obtained in this way are likely to<br />
be highly inaccurate, especially if the process is continued<br />
over a long period of time. However, this is a method that,<br />
in general, is applied only in cases where neither the basic<br />
data nor available information on population change permit<br />
the use of a more reliable method.<br />
The various combinations of letters and numerals do not<br />
lend themselves to a precise gradation from the most reliable<br />
to the least reliable. This is so not only because of the factors<br />
mentioned in the preceding paragraphs, but also because a<br />
given set of estimates may have a favorable position with<br />
respect to one part of the code and a less favorable position<br />
with respect to the other part. It is difficult, if not impossible,<br />
to rank such cases on a reliability scale. However, it may<br />
be stated with some certainty that combinations of "R",<br />
"A", and "B" with "a", "1" and "2" indicate a relatively<br />
high level of reliability, that combinations of letters and<br />
numerals at the lower end of the scale indicate a low level of<br />
reliability and that other combinations represent a rather<br />
wide variation in levels of reliability. Combinations of high<br />
letters and low numerals, or the reverse (low letters and high<br />
numerals) are unlikely to occur.<br />
The codes refer to the series of estimates for the years<br />
1948, 1949 and 1950, but not necessarily to every estimate<br />
in the series. Where a census figure is given instead of a<br />
midyear estimate and where an unofficial figure is shown<br />
the code does not apply. These cases can be identified in the<br />
table itself by reference to the census column or by the<br />
symbol "x" which indicates an unofficial figure. In other<br />
cases the method of estimation is known for one or two years<br />
but not for all three. These cases are not identified in the<br />
table because of space considerati~ns.However, since countries<br />
are generally consistent about the methods used in<br />
successive years, it is probably safe to assume that the same<br />
classification applies throughout. The code does not refer<br />
to the estimates for 1937 shown in the table, though it is<br />
quite likely that similar methods were used in the preparation<br />
of these data.<br />
Table lA presents estimates of world population by continental<br />
divisions for midyear 1950 together with data on<br />
the area in square kilometres and the number of persons per<br />
square kilometre. The area totals were obtained by summing<br />
figures for all the countries shown in table 1. The estimates<br />
of population are based mainly on the statistics for 1950<br />
presented in the same table but include allowances for those<br />
countries and population groups for which 1950 estimates<br />
are not yet available as well as other adjustments considered<br />
necessary for arriving at the best possible estimates for continental<br />
regions. Because of the uncertainty of knowledge<br />
about the population of some areas the world figure must<br />
be regarded as only a rough approximation. The estimates<br />
for Mrica and Asia are subject to considerable error; those<br />
for North and South America are somewhat more reliable;<br />
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