E = Emigrants
The Component method simulates how a population changes according to the components of
demographic change which are fertility, mortality and migration. Using the cohort-component
model has the greatest advantage of providing detailed demographic data of population growth.
However, the approach requires availability of key information on the three major components
(births, deaths, migration) by age cohort, to produce the reasonable population projections. In
Zimbabwe, the current challenge with this approach is that data on migration is very difficult to
get.
The mathematical formula was chosen mainly because it does not need inputs required by the
component method. This means that the present calculations do not take into account
immigration or emigration factors contributing to population growth. This is consistent with
other studies done in the country (Zimstat, 2009). The mathematical formula is appropriate
because the population of Zimbabwe over years has shown to continuously increase and
following closely a geometric pattern (Mandishona, 1987). Thus the geometric formula has been
used to project the population of adult Zimbabweans aged 18 plus, that is the voting population
up to 2018. The 2012 population census data was used as the base population to project the 2017
and 2018 voting population. The 2018 projections were calculated using the following geometric
formula
R = Pt*(1+r)^n
Pt - base population (last census)
R - Is the growth rate
N = number of years after the base year
The projections are presented in tables according to gender, province, district of residence and
also specific ages. Census and Survey Processing System (CSPro), a statistical data processing
software package, was used for the production of the tables in the current report. Pt = P0 + (B -D)
+ (I-E)
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