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Chapter 8: Problem 12

Define the crude birthrate (CBR) and the crude death rate (CDR). Describe how these rates are used to calculate the percent rate of growth and the doubling time of a population.

Short Answer

Expert verified
Crude Birth Rate (CBR) and Crude Death Rate (CDR) are measurements used in demography to gauge the rate of population growth. CBR is the number of births in a year per 1,000 people, and CDR is the number of deaths in a year per 1,000 people. The Percent Rate of Growth is calculated by subtracting CDR from CBR and dividing by 10: \[(CBR - CDR) / 10\]. Lastly, Doubling Time, or the number of years it would take for a population to double, is calculated by dividing 70 by the growth rate: \[70 / \text{Growth Rate}\].

Step by step solution

01

Define the Crude Birth Rate (CBR)

CBR is the number of births per 1,000 people in a population in a given year. It does not take into account the age structure of the population, and hence the term 'crude'.
02

Define the Crude Death Rate (CDR)

CDR is the number of deaths per 1,000 people in a population in a given year. Like CBR, this measure does not take account of the age structure of the population.
03

Calculating the Percent Rate of Growth

The Percent Rate of Growth is determined by subtracting the Crude Death Rate (CDR) from the Crude Birth Rate (CBR) and dividing the result by 10. The formula is: \([Population growth rate = (CBR - CDR) / 10]\). This will give the annual growth rate in percentages.
04

Calculating the Doubling Time

The doubling time of a population (the number of years it takes for a population to double in size) is determined by the formula: \([Doubling Time = 70 / \text{Growth Rate}]\) where the growth rate is the value calculated in Step 3. The number 70 comes from an approximation in the logarithmic Rule of 70, based on continuous compounding.

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