Mention two ways through which population change would be expressed
Answers
Measuring population change is necessary to determine the impact of human activity on the Earth's surface. Population change can be described using words, statistics, and graphics. Two common statistical measures of population change are the Crude Birthrate (CBR) and the Crude Death Rate (CDR). CBR and CDR are usually expressed as the number of births or deaths per 1000 people in a given population, which allows geographers to compare population dynamics in countries with different population sizes. The number of births and deaths per year in a country can be used to calculate the Rate of Natural Increase (RNI), which describes the percentage annual growth of a population.
For example, suppose a country has a total population of 250 million people, with four million births and one million deaths over a year-long period. The Rate of Natural Increase for this country would be calculated as follows:
Birthrate per 1000 population = (Births per year/Total population) * 1000 = (4,000,000/250,000,000) * 1000 = 0.016 * 1000 = 16
Death Rate per 1000 population = (Deaths per year/Total population) * 1000 = (1,000,000/250,000,000) * 1000 = 0.004 * 1000 = 4
To convert these into the RNI, you subtract the CDR from the CBR and multiply by 10 (necessary to convert the data from a per 1000 basis to a per 100, or percentage, basis).
Rate of Natural Increase = (Birthrate - Death Rate) * 10 = (16 - 4) * 10 = 1.2%
Given a RNI of 1.2%, we can predict that the population of this country will grow by 3,000,000 people in one year (250,000,000 x 1.2% = 3,000,000).
As you might imagine, comparing population trends and patterns using only statistics would be very difficult. Fortunately, there are ways to visualize statistical data to reveal meaningful geographic information. Geographers use maps to display, analyze, and compare demographic data like CBR, CDR, and RNI in different places. In the next activity, you will be asked to create choropleth maps to interpret population change in Bolivia, a country in South America. The activity will also illustrate some of the possible effects of population growth on the envirorment
An increase in the number of people that reside in a country, state, county, or city.
It is expressed in terms of:
1) Absolute Increase/ Absolute numbers: This is the no. of people added to the population each year or decade. It is obtained by subtracting the old population from the current population
2) Annual Growth Rate: This is the pace or rate of increase of population expressed in terms of percentage.