Rate of Natural Increase Explained

The question asks for the term representing the difference between the crude birth rate and the crude death rate in a population.

• Crude Birth Rate (CBR): This is the number of live births per 1,000 people in a population per year.
• Crude Death Rate (CDR): This is the number of deaths per 1,000 people in a population per year.

The difference between these two rates indicates how much a population is growing or shrinking purely due to births and deaths, without considering migration.

This difference is formally known as the Rate of Natural Increase (RNI).

The formula is:

$ \text{Rate of Natural Increase} = \text{Crude Birth Rate} - \text{Crude Death Rate} $

A positive RNI means births exceed deaths, leading to natural population growth. A negative RNI means deaths exceed births, resulting in natural population decline.

Analyzing Other Options

• Population momentum: Refers to the continued population growth that occurs even when fertility rates have fallen, due to a large young population entering reproductive age.
• Demographic transition rate: A broader term that describes the overall change in population size, often involving stages of high birth/death rates shifting to low birth/death rates. It generally encompasses natural increase and migration.
• Net migration rate: This measures the difference between the number of immigrants (people entering) and emigrants (people leaving) per 1,000 population. It focuses solely on movement across borders, not births or deaths.

Therefore, the difference between crude birth rate and crude death rate specifically defines the Rate of Natural Increase.