Which term describes the difference between birth rate and death rate, excluding migration?

The Natural Increase Rate refers to the difference between the birth rate and the death rate in a population. This metric specifically focuses on how many more individuals are born than die within a given time frame, forming a fundamental aspect of demographic studies. It provides insight into population growth by excluding factors such as migration, which can significantly affect overall population numbers but do not pertain to changes in the natural population due to births and deaths.

Understanding the natural increase is essential for demographic analysis because it indicates whether a population is growing or declining based solely on its reproductive health and mortality rates. For instance, a high birth rate combined with a low death rate results in a high natural increase rate, signifying a growing population, while the opposite indicates a declining population.

In contrast, other terms such as immigration rate refer specifically to the movement of people into a region, death rate measures the number of deaths in a population, and population density quantifies how many individuals live in a given area. None of these terms encapsulate the specific relationship of birth versus death rates without the influence of migration. Thus, the Natural Increase Rate is the precise term that aligns with the question's focus.