Presentation by amin
- 1. Presentation on LIFE TABLE Presented by Aminul Islam ID:14115570 Department of Population Science and Human Resource Development, University of Rajshahi
- 2. Life table : A historical perspective Defination of Life table Types of Life table Applications of Life table Assumptions of Life table Construction of a Life table Conclusion
- 3. Edmond Halley was the first person to show us how to properly calculate and construct the life table. Halley was a british astronomer , geophysicist, mathematician, meteorologist who is best known for computing the orbit of Halley’s comet. He calculated the first ever life table sometime 300 years back . Till date the same methodology is followed with only slight variation.The first life table had been published in London in 1662 in a book entitled Natural and Political Observations Made upon the Bills of Mortality.
- 4. The life table is a life history of a hypothetical group or cohort of people, as it is diminished gradually by death.The record begins at the birth of each member and continues until all died.” Thus a life table is a mathematical device which shows the life span of persons up to a particular age or their probable date of death relates to a cohort of people born at the same time until they die. A life table can be constructed for a country and an area on the basis of sex, occupation, race, etc.
- 5. Current/Period vs. Generation/Cohort Complete vs. Abridged Single vs. Multiple Decrement Increment/DecrementTables
- 6. COHORT LIFE TABLE • The cohort life table presents the mortality experience of a particular birth cohort. • All persons born in a year, from the moment of birth through consecutive ages in successive calendar years. • The cohort life table reflects the mortality experience of an actual cohort from birth until no lives remain in the group. PERIOD LIFE TABLE Period LifeTable summarises the age specific mortality conditions pertaining to a given or other short time period.
- 7. COMPLETE A complete life table contains data for every year of age. ABRIDGED An abridged life table typically contains data by 5- or 10-year age intervals . A separate group is made for age group 0-1 years . In India a 5 year interval is selected.
- 8. SINGLE DECREMENTAL MULTIPLE DECREMENTAL
- 10. To find the number of survivors out of 1,000 or 10,000 or over birth or at any age thereafter say, At the age of 5, to find number of children likely to enter primary school. At the age of 15, to find number of women entering fertile period. At age of 18, to find number of persons become eligible for voting.
- 11. • To find expectation of life or longevity of life at birth or any other age. • Increase in longevity of life means reduction in mortality, thus life table is another method applied to compare mortality of two places, periods, professions or groups.
- 12. • To find survival rate after treatment in chronic disease like tuberculosis, cancer or after cardiac surgery by modified life table. • Helps to project population estimates by age & sex.
- 13. 1. The cohort is closed. No migration, No birth, only deaths occur. 2. People die according to schedule (fixed) 3. Cohort originate as 1,000, 10,000, 100,000, 1,000,000 called ‘radix’. 4. At each age (except first few year of life) death are evenly distributed between one birth day and next birth day. 5.The cohort of life tables are generally constructed separately for males and females Assumptions of life table
- 14. To construct a life table, two things are required: 1.Population living at all individual ages in a selected year. 2.Number of deaths that occurred in these ages during the selected year.
- 15. 1. AGE (x) 2. NUMBER ALIVE AT BEGINNING OF YEAR (lx) 3. NUMBER DYING IN THE YEAR (dx) 4.PROBABILITY OF DYING(qx) 5.PROBABILITY OF SURVIVING(px)
- 16. PROCEDURE: We use column 2 multiplied by column 3 to obtain column 4. Then column 4 is subtracted from column 3 to obtain the next row’s entry in column 3.
- 17. 1. 2. 3.
- 18. 4. 5. 6. 7.
- 19. EXAMPLE: 100,000 births ( row 1, column 3) have an infant mortality rate of 46.99/thousand (row 2, column 2), so there are 4,699 infant deaths (row 3, column 4). This leaves 95,301 left (100,000 – 4,699) to begin the second year of life (row 2 column 3).
- 20. If we stopped with the first four columns, we could still find out the probability of surviving to any given age. e.g. in this table, we see that 90.27% of non- white males survived to age 30.
- 21. Column: 6. THE NUMBER OF YEARS LIVED BY THE POPULATION IN YEAR X (Lx) 7. THE NUMBER OF YEARS LIVED BY THE POPULATION IN YEAR X AND IN ALL SUBSEQUENT YEARS (Tx) 8. THE LIFE EXPECTANCY FROM THE BEGINNING OF YEAR X (ex)
- 22. The total number of years lived in each year is listed in column 5, Lx. It is based on two sources. One source is persons who survived the year, who are listed in column 3 of the row below. They each contributed one year. Each person who died during the year (column 4 of the same row) contributed a part of year, depending on when they died. For most purposes, we simply assume they contributed ½ a year.
- 23. The entry for column 5, Lx in this table for age 8-9 is 94,321. Where does this number come from? 1. 94,291 children survived to age 9 (column 3 of age 9-10), contributing 94,921 years. 2. 60 children died (column 4 of age 8-9) , so they contributed ½ year each, or 30 years. 3. 94,921 + 30 = 94,321.
- 24. 1. Lx = 96,254 2. 95,301 contributed one year 3. 96,254 - 95,301 = 953 years, which must come from infants who died 0-1 4. 4,699 infants died 0-1 5. 953/4,699 = .202 or 1/5 of a year, or about 2.4 months
- 25. The top line of Column 6, or Tx=0 , is obtained by summing up all of the rows in column 5. It is the total number of years of life lived by all members of the cohort. This number is the key calculation in life expectancy, because, if we divide it by the number of people in the cohort, we get the average life expectancy at birth, ex=0, which is column 7.
- 26. For any year, column 6, Tx, provides the number of years yet to be lived by the entire cohort, and column 7, the number of years lived on average by any individual in the cohort. (Tx/lx) Thus column 7 is the final product of the life table, life expectancy at birth, or life expectancy at any other specified age.
- 27. Px Midyear population between ages x and x+1 Dx Number of deaths between ages x and x+1 mx Age-specific death rate ax Average fraction of the last year of life lived by those living between x and x+1 qx Probability of dying between age x and x+1 lx Number of people surviving to age x out of the life table cohort dx Number of deaths between age x and x+n out of the life table cohort Lx Number of person years lived between age x and x+1 Tx Total number of person years lived after age x ex Life expectancy at age x
- 28. 1. 2. 3.
- 29. 4. 5. 6. 7.
- 30. Life expectancy at birth in the US now is 77.3 years. This means that a baby born now will live 77.3 years if………….. that baby experiences the same age- specific mortality rates as are currently operating in the US.
- 31. The Life table methodology was first adopted some 300 years back. Credit must be given to Edmond Halley who used his innovative mind to create this statistical tool. In an era of sophisticated and advanced statistical applications, Life tables have survived the test of time. Life table is an old method and probably in this era may not be gold but definitely it has not lost its shine and is still being used to calculate some vital parameters(life expectancy, contraceptive failure).
- 32. Who knows one day with certain modifications this old methodology may ascertain its value as the gold methodology.