Basic Measures of Mortality and Life Table

Mortality and Population Health: A portion of the world’s population has struggled to keep up in the fight against early death and in some regions the 

Mortality: Mortality refers to the number of deaths taking place in a given internal in a specific population. Another says that “The postnatal gestation of vital function with possibility”

Demographic Definition of Death

“Demographers operationally defined death as the event described in writing by a death certificate signed by a licensed physician or medical examiner”.

Basic Measures of Mortality

A. Crude Death Rate (CDR): Number of deaths in a given year per 1000 mid-year population.

        

(Number of deaths/year)/(Mid-year population)×1000

CDR=D/P  ×1000

Problems 

• Mortality is age-specific.
• Population typically vary in their age compositions (some are older, others young this difference must be taken into account).
• CDR is insensitive to age-composition.
• Comparisons across populations based on CDR can lead to misleading conclusions.

CDR points to note

• Risks of death change by age, so CDR is affected by population age structure.
• Aging population can have rising CDR’s even as the health conditions are improving.
• LDC’s with very young population will have lower CDR’s than MDC’s even through their overall health conditions are poorer.
• Therefore mortality comparisons across countries should always is mortality indicators that are adjusted for differences in age composition.

B. Age Specific Death Rates. Number of deaths per year in a specific age group per 1000 persons in the age group.

                                              Da/Pa  ×1000

     where,Da=Number of deaths in age group a

               Pa=Mid year population in age group a

Why age specific death rates

• Can compare mortality at different age.
• Can compare mortality in the same age groups over time and between countries and areas.
• Can be used to calculate life tables to create an age-independent measure of mortality.

Cause Specific death rates

Number of deaths attributable to a particular cause divided by population at risk, usually expressed in deaths per 100000.

DC/P  ×10000

C. Infant Mortality Rate: Number of deaths of infants under age per year. Per 1000 live births in the same year.

IMR=(Number of deaths of infant in a given year)/(Total live birth in that year)  ×1000

When Important

• The IMR is a good indicators of the over health status of a population.
• The IMR is sensitive to levels and change in socio-economic conditions of a population.
• It is a major determinant of life expectancy at birth.

D. Maternal mortality rate: Number of Women who die as a result of complication of pregnancy or child bearing age in the population

(Numbrt og maternal deaths)/(Number of women ages(15-49) )  ×100000

The Life Table

Life tables are used frequently in the biological and social sciences and in many applied industrial situations. For demographers, the life table is a tool for describing a population’s mortality using period cross-sectional, age specific death rate. In this sense, the life table describes the survival experience of a fictional cohort subjected to the current age-specific death rates of an actual population over the cohort imagined life time. This is generally referred to as the period life table.

A cohort life table is computed from historical data for a birth cohort that was born many years ago and now exists. 

Life table 

A life table is a concise way of showing the probability of a member of a particular population to or dying at a particular age. There are two types of life table 

1. Period life table.
2. Cohort life table.

Period life table: For demographers, life table is a tool for describing a populations mortality using period cross-sectional age specific death rates of an actual population over the refer Cohorts imagined life time. This is generally as the period life table.

Cohort life table: A Cohort life table is computed from historical data for a birth cohort that was born many years ago and it now extinct. A Cohort life table is base on mortality experience over the entire life of a cohort of persons born during a relatively short period of the year.