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This article throws light upon the top five methods used for measuring death rate. The methods are: 1. Crude Death Rate (CDR) 2. Age Specific Death Rate (ASDR) 3. Cause Specific Death Rate (CSDR) 4. Infant Mortality Rate (IMR) 5. Standardised Death Rate (SDR).
Method # 1. Crude Death Rate (CDR):
The crude death rate is the number of deaths per 1000 people in a year in relation to the total population.
It can be calculated as follows:
Crude Death Rate = 
x K
where
D= Total registered deaths in a year
P = Total mid-year population of that year
K= 1000
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In other words,
CDR= 
x 1000
If the total mid-year population of an area is 50,000 and the number of deaths is 500, then
CDR = 
x 1000=10. 50,000
It indicates that the crude death rate is 10 per 1000 people.
It is a simple method to measure the death rate because it takes only the data of total mid-year population and total deaths. But it has certain defects. First, it combines the death rates of different age groups. So it fails to give a correct measure of mortality because in less developed countries infant mortality rates, maternal death rates and old people death rates are high.
Second, it is also not possible to make inter-regional comparisons in a country due to variations in death rates, as noted above. Third, the sources of data for population and deaths are different. The population data are based on the census and that of deaths on registration authorities. This is unscientific.
In order to overcome the first two limitations, age specific deaths rate and infant mortality rate are calculated.
Method # 2. Age Specific Death Rate (ASDR):
As the death rates in the case of infants and old people are high and that of young people are low, it is advices to classify people under differences categories according to their age groups.
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The age specific death rate is calculated as under:
Age Specific Death Rate= 
x K
where,
DA = Number of deaths in a particular age group
PA = Mid-year population of the age group
K= 1000 In other words,
ASDR = 
x1000
White calculating the age specific death rate, the age group of 5 year interval is taken such as 0-4, 5-9, 10-14 years, etc.
Method # 3. Cause Specific Death Rate (CSDR):
Death is a biological event and may occur due to any reason. The causes responsible for death may be accident, injury, child birth, pregnancy, fever, specific diseases of childhood and old age, etc. The formula for measuring cause specific death rate is
CSDR=
x K
Dc= Number of deaths due to a particular cause in a year
D = Total number of mid-year deaths
K= 1000
Data regarding deaths due to different causes are helpful in taking preventive measures against respective factors for death. In addition, we can know the causes of sex-wise and group-wise deaths, and of males and female deaths in particular age groups.
Death Rate by Cause or Cause Specific Death Rate:
Deaths may be caused by malaria, AIDS, typhoid, accident, etc. Such cause specific deaths can be computed with the following formula
Cause Specific Death Rate = 
x K
where,
Dc= Number of deaths due to a particular cause in a year
P = Mid-year population in that year
K= 1000
On the basis of the death rate due to a particular cause, the authorities can compare the death rates of different places and take remedial measures.
Method # 4. Infant Mortality Rate (IMR):
A child in the age group of 0-1 is called an infant. According to Barclay, “Infants are defined in demography as an exact age group, namely, age ‘zero’, or those children in the first year of life, who have not yet reached age one.”
The formula for computing infant mortality rate:
Infant Mortality Rate =
x 1000
Where
DI= Number of deaths among infants registered during the year
B = Number of registered births in the same year
K= 1000
In other words,
Infant Mortality Rate = 
x 1000
If the number of registered deaths among infants in a specified year is 5800 and the number of registered births in the same year is 72000, then
Infant Mortality Rate = 
x 1000 = 80.5.
This indicates that 80.5 infants per 1000 newly born babies died in that particular year.
The problem in measuring the infant mortality rate in underdeveloped countries is that people normally do not report infant deaths, still births and abortions. Another problem is that an infant born in the previous year might have died in the computing year. This measure does not take into account such problems.
However, the above method can also be used to calculate maternal death rate.
Causes of Infant Mortality:
Many factors are responsible for infant mortality. They are endogenous and exogenous factors. The former relate to biological and the latter to socio-economic, cultural and environmental factors.
We discuss them briefly as under:
(1) Endogenous Factors:
These are biological factors relating to the age of the mother, the order of pregnancy or birth, period of spacing between two births, pre-mature birth, weight of infant at birth, etc. These factors lead to deaths of infants who do not complete 4 weeks of life.
Since they are related to the formation of foetus in the womb, they are called neo-natal mortality rates. Neo-natal deaths occur if the mother is of low age, the baby is born prematurely, the weight of the baby is very low, the spacing between two babies is hardly one year, etc.
(2) Exogenous Factors:
These factors relate to post-neo-natal deaths of those infants who die between 28 days and one year of life. They are caused by diseases of respiratory, circulatory and digestive systems; lack of medical facilities; malnutrition; insanitary conditions, illegitimacy, etc.
Method # 5. Standardised Death Rate (SDR):
The standardised death rate is computed to compare the death rates of two different populations. According to Thomson and Lewis, “The standardised death rate, based on age specific death rates, supplies a simple and accurate basis for comparing the death rates of different populations.”
Standardised death rates are of two types – direct and indirect.
Direct Standardised Death Rate:
In the case of direct standardisation death rates, there are two types of procedures for computing them. One is to apply different age specific rates to standard population. The second method is to take the population distribution of any locality as the standard population and to multiply it with the age specific death rates.
The following formula is applied:
Standardised Death Rate = 
where,
Ps = Standard population of a locality
DL= age specific death rate of local population
To take an example.
Suppose there are two towns A and B with the following data on population and age specific death rates:
As per the above formula, the standardised death rate of town A is
The standardised death rate of town B is
On the basis of these standardised death rates, it can be concluded that the death rate in town B is higher than in town A.
Indirect Standardised Death Rate:
In the case of indirect standardised death rate, the age specific death rate of a locality is taken as the standard for computation and the following formula is applied
Indirect Standardised Death Rate= 
where,
PL = Population of the locality
Ds = Standardised age specific death rate