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Ptb
Where:

NIR: Natural Increase Rate of population;
B: Total number of live births in the reference period;
D: Total number of deaths in the reference period;

Ptb: Average population in the reference period.
Growth rate of population (growth rate) reflects the increase/decrease
of the population in reference period due to natural increase and net-migration.
Growth rate of population is expressed as a percentage or per mille.
In-migration rate are the number of people from different territorial
units (out-migration place) in-migrate to a territorial unit in the reference
period (usually a calendar year) on an average per 1,000 population of that
territorial unit (in-migration place).

Formula:
I
IR (‰) = × 1000
Ptb
Where:

IR: In-migration rate;
I: Number of in-migrants in 12 months prior to the reference period;

Ptb: Average population in the reference period.
Out-migration rate reflects the number out-migrants of a territorial unit
in the reference period on average per 1,000 population of that territorial unit.
Formula:
O
OR (‰) = × 1000
Ptb

Where:
OR: Out-migration rate;
O: Number of out-migrants in 12 months prior to the reference period;
Ptb: Population up to the reference time-point.
Net-migration rate reflects the status of in-migration and out-
migration of population into/out from a territorial unit in the reference
period. It is the difference between number of in-migrants and number of

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