1. CHAPTER 16
Life Tables

2. OUTLINE 16.1 GENERAL USE OF LIFE TABLES
16.1            GENERAL USE OF LIFE TABLES
Discusses life tables, used by demographers and researchers to describe the mortality or longevity of a population
16.2            CURRENT LIFE TABLES
Analyzes a current life table
16.3            FOLLOW-UP TABLES
Describes a neat technique for tracking survival of patients with chronic diseases

3. LEARNING OBJECTIVES
1.                    Distinguish among the three types of life tables
2.                    Identify and be able to compute the components of a current life table
3.                    Compute measures of mortality and longevity from a life table
4.                    Construct a follow-up life table

4. GENERAL USE OF LIFE TABLES
A.      Used by demographers to measure and analyze the mortality or longevity of a population or one of its segments
B.       Used by insurance companies to compute premiums
C.       By research workers to determine whether the differences in mortality or longevity of two groups are significant
D.      Employed to predict survival or the likelihood of death at any time
E.       Life table analysis can be fundamental to the solution of many public health and medical problems
F.       Current life table illustrates how age-specific death rates affect a population
G.       Cohort Life Table – follows a defined group (a cohort) from birth (or some measurable point in time) until the last person in the group has died – also know as a generation life table)

5. CURRENT LIFE TABLES AGE INTERVAL –
is the period of time between two exact ages stated
AGE-SPECIFIC DEATH RATE –
The numerator for this rate is the average number of deaths per year in a 3-year period, divided by the July 1 average population for each of the 3 years
CORRECTION TERM () –
defines and adjusts for maldistribution

6. CURRENT LIFE TABLES CORRECTED (ESTIMATED) DEATH RATE –
denotes the proportion of persons who are alive at the beginning of the age interval but die during that interval
NUMBER LIVING AT BEGINNING OF AGE INTERVAL –
the number of persons, starting with the original cohort of 100,000 live births, who survive to the exact age marking the beginning of each interval.

7. CURRENT LIFE TABLES NUMBER DYING DURING AGE INTERVAL –
number of the original 100,000 who die during each successive age interval – calculated by multiplying the proportion dying during the interval by the number alive at the beginning of the interval
PERSON-YEARS LIVED IN INTERVAL –
totality of years lived by the survivors of the original 100,000 between the ages x and (x + n)
for all intervals except the last, for which

8. CURRENT LIFE TABLES EXPECTATION OF LIFE –
the average number of years of life remaining to those who survive to the beginning of the age interval – calculated by dividing the number of person-years lived after a given age by the number who reached that same age
Odds of surviving from birth to age 65

9. CURRENT LIFE TABLES
A.      Median age at death – age to which precisely half of the cohort survives
B.      Life span
1.                  the age that persons are likely to reach, given optimal conditions
2.                  defined as that age reached by the longest-lived 0.1% of the population – currently quite close to 100 years

10. FOLLOW-UP TABLES
A.        Provides a basis for answering the question “how long do I have”
B.        Often used to evaluate the relative effectiveness of alternative modes of treatment by computing the probability of survival of patients treated using each mode
C.        Particularly useful because it utilizes the experience of each person for the entire time he or she is in the study; that is, the method considers the period of exposure in terms of person-years or other appropriate units
D.       Data for life tables identically, provided that
1.                    death rates do not change materially over time
2.                    exposure to the disease prior to treatment is not increasing with time

11. CONSTRUCTION OF FOLLOW-UP TABLE
A.        To construct a follow-up table:
1.                    you need to know the follow-up period after some event
2.                    to ensure accuracy, you need well-defined starting and end points
B.        Given a know period of observation for each patient, you can then tally
1.                    how many survive
2.                    how many die
3.                    how many are lost to follow-up during the first and subsequent years of the study

12. CONSTRUCTION OF FOLLOW-UP TABLE
C.                  Construction of the table
1. = total number of patients who begin the study
2. = probability of surviving the first year
3. = persons lost to follow-up
4. = withdrawals from the study alive
5. Assumed that and live half way through the interval

13. CONSTRUCTION OF FOLLOW-UP TABLE
  Estimate of surviving the second year of follow-up:
Probabilities of surviving subsequent year are computed similarly
Probability of surviving the first five years is

14. CONSTRUCTION OF FOLLOW-UP TABLE
A.      5-year survival rate – commonly used in cancer research as a measure of a treatment’s effectiveness
B.      Determining statistical significance between , the xth-year survival rate of a treatment group, and , the xth-year survival rate of a control group
where and are standard errors for the two groups and Z is the normal score
Standard error equation

15. CONCLUSION
Life tables provide excellent means for measuring mortality and longevity. The current life table shows the effects of age-specific death rates on a group. From this table, measures of mortality and life expectation can be computed. Whereas the current life table presents a hypothetical picture of the effects of present mortality rates, the cohort life table is an actual historical record of the mortality of a group followed through life. The follow-up life table considers the experiences of persons from event to event during the period of a study.

16. Pareto chart Vilfredo Pareto
(Italian economist/sociologist, )
In the real world a minority of causes lead to the majority of problems.
Ergo: The Pareto Principle
80/20 Rule

17. Swift V-12 Sales by Age Group
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Sales ($M) UP
Customer Age Group

18. Swift V-12 Sales by Age Group
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Sales ($M)
100%
90%
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Cum % UP
Customer Age Group

19. Cause and Effect Diagrams Ishikawa
Sometimes called a “fishbone diagram”
Benefits
Creating the diagram itself is an enlightened, instructive process.
Such diagrams focus a group, thereby reducing irrelevant discussion.
Such diagrams separate causes from symptoms and force the issue of data collection
Such diagrams can be used with any problem

20. Fishbone diagram
Cause
Cause
Cause
EFFECT
Cause
Cause
Cause

21. Fishbone diagram Solder Defects Machine Operator Materials Environment
Methods
Measurement

22. Fishbone diagram Materials Solder Defects Handling Solder Methods
Solderability
vendors
storage
age
Solder
Contamination
Solder
Defects
Methods
Machine
Measurement
Operator
Environment
Parts
Flux

23. Run and Control Charts (Trend chart)
Variable
Time
Variable
Time
Control

24. Steps: Planning a Health Survey
Make a written Statement of the purpose
Formulate Objectives and Hypotheses
Specify the target population
List the variables
Review existing data
Decide how to collect data
Establish a time frame
Design the questionnaire
Pretest the questionnaire
Obtain informed consent
Select the sample
Collect the date
Edit and code the data
Analyze the data
Report the findings