1. Lecture Series on
Biostatistics
No. Biostat - 5
Date: 10.08.2008
MEASURES OF MORTALITY
Dr. Bijaya Bhusan Nanda,
M. Sc (Gold Medalist) Ph. D. (Stat.)
Topper Orissa Statistics & Economics Services, 1988
bijayabnanda@yahoo.com

2. CONTENTS
 Introduction
 Determinants of Mortality
 Uses of Mortality data
 Sources of Mortality data
 Measures of Mortality
 Life Table

3. LEARNING OBJECTIVE
 They will be able to compute
different indices of mortality.
 They will be able to spell out general
determinants of mortality.
 They will be able to spell out
usefulness of mortality indicators.

4. INTRODUCTION
Death:
“the permanent disappearance of all evidences of
life at any time after birth” (WHO).
• Mortality:
• A demographic event – Average risk of dying of a
person in the group during a time span.
• This is one of the three determinants of
population change i.e. fertility, mortality and
migration.
• Factors of mortality patterns:
• Endogenetics (biological):
• Exogenetic(environmental):

5. DETERMINANTS OF MORTALITY
 Vary over Space and Time
Classified in to three categories:
Demographic structure- Age, Sex Composition etc.
Social advancement- Age at marriage, Adequacy of
medical facilities, General condition of nutrition,
Housing and Sanitation, Literacy, Religion, Caste
and Community beliefs etc.
Economic development- Occupation, Standard of
living/ per capita income , Type of economy etc.

6. USES OF MORTALITY RATE
 Useful for projecting the future size of the
population
 Identify population groups that are at high risk
and in need of health service
 Indicatives of quality of life and expectation of
life at birth.
 Useful guides to planners
 Helpful to insurance companies

7. SOURCES OF MORTALITY DATA
There are two sources:
I. Direct source
 Registration of vital events
 Sample Registration Surveys
 National Family Health Surveys
I. Indirect source
 Age data of two consecutive censuses may be
used to estimates death rates
 Demographic year book: U.N. Publication
 World Health Organization (WHO) also
provides data

8. MEASURES OF MORTALITY
 It is the quantitative and statistical devices
to label the risk of mortality to which a
population is exposed over a period of time.
Different measures of mortality:-
 Crude death rate:
Crude death rate (d) =( D/P)*1000
D= No. of deaths in a population during a
given calendar year
P= average number of persons living in the
population during the year

9.  Merits
 requires minimum data on mortality
 Easy to interpret
 Demerits
 Since the risk of death is not uniform
for different segments of population
(age, sex etc.) CDR is a crude measure
and cant be used directly for comparing
the levels of mortality in two or more
countries.

10. Age Specific Death Rates(ASDR)
Dx
Age specific death rate (ASDR) =nMx= n
× 1000
n Px
nDx = No. of death between x and x+n in the yr.
nPx = No. of persons aged between x and x+n in
the middle of yr.
Note: Line graph of ASDR at y-axis and age at
x-axis it shows J-shape pattern for developed
countries and U-shape pattern for developing
countries because in developing countries
mortality rates are comparatively higher at
younger ages.

11. Infant Mortality Rate (IMR)
No. of infants dying under one year of age in a
year per thousand live birth in a given
geographical region.
D0
IMR= × 1000
B
D0 : No. of infants who died before celebrating
their first birthday.
B : Total No. live births occurring in that year
and geographical region.

12. Child Mortality Rate (CMR)
Defined as the total number of deaths of
children aged 1 to 4 yrs. per 1000 population
of the same age in a given year and
geographical region.
No. of deaths of children aged 1to
4 yr in given yr and region
CDR = × 1000
tot. population aged 1 to 4 in
the given yr and a given region

13. Neonatal Mortality Rate (NMR):
No. of infants dying within the first 4 weeks or up
to 28 days of life per 1000 live birth in a year and
geographical region.
Deaths of infants up to 4 weeks
NMR = × 1000
No. of live births
Early Neonatal Mortality Rate (NMR):
No. of infant deaths during the first seven days of
life per 1000 live births in a year and geographical
region.
ENMR = Deaths of infants in the first week of life
× 1000
No. of live births

14. Perinatal Mortality Rate (PMR)
No. of still births/ late foetal deaths (after 28
weeks of gestation) plus deaths within first
week of life in a year and geographical region
for 1000 births (live and still) in a year and
region.
Foetal deaths after 28weeks of gestation +
deaths of newborns within 7days
PMR= × 1000
No. of live births during the same year

15. Post Neonatal Mortality Rate (PNMR)
Number of infants deaths after 28 days to
less than 1yr (between 4 weeks to 52 weeks)
of age per 1000 live births in a given year.
No. of deaths of newborns between
4weeks or less than 1yr old in a year
PNMR= × 1000
No. of live births during the same yr

16. Maternal Mortality Ratio (MMR)
No. of deaths of women while pregnant or
within 42 days of termination of pregnancy
from any cause related to pregnancy/
childbearing and child birth per 100,000 live
births in a given year.
Deaths of pregnant women and women
after termination of pregnancy within 6
weeks from any cause related to
pregnancy
MMR= × 100000
No. of live births during the same year

17. Maternal Mortality Rate (MMRT)
Number of maternal deaths while pregnant
or within 42 days of termination of
pregnancy from any cause related to
pregnancy/ childbearing and childbirth per
100,000 women in reproductive ages 15-49.
No. of maternal deaths of
women in age 15-49
MMRT = × 1000
No. of women in age 15-49
in a given yr

18.  Foetal Death:
Deaths prior to the complete expulsion or
extraction from its mother of a product of
conception at any time of pregnancy.
 Still Birth
Death of foetus after completing 28 weeks and
till the time of birth.
 Incidence Rate
Number of NEW cases of specified diseases
occurring in a defined population during a
specified period of time.

19. (Continued…………)
No. of new cases of specified
disease during a given period
Incidence rate = × 1000
Population at risk
Prevalence Rate
Number of all current cases (old and new) of a
disease at one point in time in relation to defined
population. No. of new and old cases
of specified disease existing
at a given point in time
Prevalence rate = × 1000
Estimated population at
the same point in time

20. s
th
ks of gestation completed
Toddler Post Late Early Still Birth
Death Neonatal Neonatal Neonatal
Death Death Death
Neonatal
Death
Perinatal Death
Infant Death
Time Reference for Mortality in Childhood and Infancy

21. Limitations of Measures of Mortality
 The risk in a population may vary
largely with various socio-economic
and biological traits.
 The lack of reliable and requisite data
presents serious problem sometimes of
considerable magnitude.

22. Exercise: Calculate the crude and Age specific death
rates of the population from the following data
Age-group Population Deaths
(Years)
Under 10 20,000 600
10-20 12,000 240
20-40 50,000 1,250
40-60 30,000 1,050
Above 60 10,000 500

23. Expectation of Life
 The curate Expectation of life, (ex) gives the
average number of completed years of life lived
by the cohort l0 after age x by each of lx
persons attaining that age. The complete
expectation of life, denoted as exo, measures the
average number of years a person of given age
can be expected to live under the prevailing
mortality conditions. It gives the number of
years of life entirely completed and includes
the fraction of the year survived in the year in
which death occur, which on the average can
be taken to be ½ years. exo = ex +1/2

24. REFERENCE
 An Introduction to the Study of
Population, Bhaskar D. Mishra
 Techniques of demographic Analysis,
K. B Pathak, F. Ram
 Fundamentals of Applied Statistics,
S.C Gupta and V. K Kapoor.

25. THANK YOU