Life Expectancy - Life Tables Flashcards
What is a life table?
Tables that are based on the probability of dying between one age (or age group) & the next age (or age group).
How does a period life table work?
Life expectancy is calculated using age specific mortality rates (ASMRs) of that particular period.
How does a cohort life table work?
Life expectancy is calculated using ASMR that change over time as people age.
What is the difference between full life tables and abridged life tables?
Abridged life tables use age groups whereas full life tables use single years of age.
Why do we focus on the ‘Period Abridged Life Table’?
We assume a stationary population.
What does nMx mean?
Age-specific death rate between ages x and x+n.
What does lx mean?
Number of people alive at exact age x.
What does nQx mean?
Probability of dying between exact ages x and x+n.
What does nPx mean?
Probability of surviving from exact age x to exact age x+n.
What does nDx mean?
Number of deaths between exact ages x and x+n.
What does nLx mean?
Average number alive in the interval between exact ages x and x+n, OR number of person-years lived in the interval between exact ages x and x+n.
What does Tx mean?
Total population aged x and over, OR total number of person years lived from exact age x.
What does Ex mean?
Expectation of life at exact age x.
What does x mean?
The age at the start of an interval.
What does n mean?
The number of years in an interval.
What does person-years mean?
Sum of the years population has lived during a fixed interval/whole life.
What does a(x) mean?
Fraction of the age interval lived by those in the cohort
population who die in the interval.
How do you calculate the age-specific death rate?
Number of deaths at age x divided by population at age x.
How do you calculate nQx?
n(nMx) divided by ( 1+ n(1-ax)nMx))
How do you calculate nPx?
nPx= 1 – nQx
What does I(x+n) mean?
The number of people alive at the start of interval.
How do you calculate I(x+n)?
No. alive at start of interval = No. alive at start of previous interval x Probability of surviving
I(x+n) = l(x) multiplied by nPx
List the assumptions of a period life table.
- A ‘Stationary Population’
- Population growth is constant
- Constant age structure
- Closed to migration
