Human Life Tables and Survivorship Curves

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Human Life Tables and Survivorship Curves

Test hypotheses about human survivorship using:
PURPOSE: Test hypotheses about human survivorship using: Life tables life expectancy Survivorship curves

HO: The life expectancy of women is the same as for men or less than that of men. HA: Women have a greater life expectancy than men. BRB R.I.P.

HO: Men do not have a greater life expectancy during child bearing years. HA: Men have a greater life expectancy than women during child bearing years. BRB R.I.P. 4

HO: Human life expectancy has not increased over the period of time during which people were buried in our study area cemeteries. HA: Human life expectancy has increased over this time period BRB R.I.P.

What are life tables? A life table contains age-specific survival and mortality rates in a population. It also contains fecundity and age distribution information. Life tables come in 2 varieties: Cohort life table: Follows a group of individuals born at the same time. Static life table: Constructed by recording the age at death of a large number of individuals. This is what we’ll be making.

X = a reference number we assigned to refer to the different classes
Life Tables Age Class x dx nx lx ax 0-5 1 6-10 2 11-15 3 Etc. X = a reference number we assigned to refer to the different classes

X = a reference number we assigned to refer to the different classes
Life Tables Age Class x dx nx lx ax 0-5 1 x-1 6-10 2 11-15 3 Etc. X = a reference number we assigned to refer to the different classes

X = a reference number we assigned to refer to the different classes
Life Tables Age Class x dx nx lx ax 0-5 1 6-10 2 11-15 3 x+1 Etc. X = a reference number we assigned to refer to the different classes

dx Life Tables Age Class x nx lx ax 0-5 1 6 6-10 2 11-15 3 Etc.
Etc. dx= the number of individuals that die in the x age class.

nx Life Tables Age Class x dx lx ax 0-5 1 6 6-10 2 11-15 3 Etc.
How many? 6-10 2 11-15 3 Etc. nx= total number of individuals surviving to the x age class. nx = nx-1- dx-1

nx Life Tables Age Class x dx lx ax 0-5 1 6 100 6-10 2 11-15 3 Etc.
How many? 11-15 3 Etc. nx= total number of individuals surviving to the x age class. nx = nx-1- dx-1

lx Life Tables Age Class x dx nx ax qx 0-5 1 6 100 6-10 2 94 lx =
11-15 3 92 Etc. (lx) Survivorship: Portion of population that survived to the x age class

lx Life Tables Age Class x dx nx ax qx 0-5 1 6 100 6-10 2 94 .94 lx =
11-15 3 92 .92 Etc. (lx) Survivorship: Portion of population that survived to the x age class

ax Life Tables Age Class x dx nx lx qx 0-5 1 6 100 6-10 2 94 .94 11-15
3 92 .92 ax = Etc. ax = Given you reach the x age class, what is the probability you live to the NEXT age class.

ax Life Tables Age Class x dx nx lx qx 0-5 1 6 100 6-10 2 94 .94 11-15
=94/100 6-10 2 94 .94 11-15 3 92 .92 ax = Etc. ax = Given you reach the x age class, what is the probability you live to the NEXT age class.

qx Life Tables Age Class x dx nx lx ax 0-5 1 6 100 .94 6-10 2 94 .98
11-15 3 92 .92 qx = Etc. qx = Given you reach the x age class, what is the probability you do NOT live to the NEXT age class.

qx Life Tables ax + qx = 1 Age Class x dx nx lx ax 0-5 1 6 100 .94
6-10 2 94 .98 11-15 3 92 .92 Etc. ax + qx = 1

qx Life Tables ax + qx = 1 Age Class x dx nx lx ax 0-5 1 6 100 0.94
0.06 6-10 2 94 0.98 0.02 11-15 3 92 0.92 Etc. ax + qx = 1 Make three: Males, Females, and Totals for your group’s data

Example Life Table x Dx Nx lx ax qx 1000lx log1000lx 0-5 1 4.00 250.00
1.00 0.98 0.02 3.00 6-10 2 0.00 246.00 984.00 2.99 11-15 3 16-20 4 245.00 0.99 0.01 980.00 21-25 5 242.00 0.97 968.00 26-30 6 239.00 0.96 956.00 2.98 31-35 7 36-40 8 2.00 236.00 0.94 944.00 2.97 41-45 9 234.00 936.00 46-50 10 12.00 233.00 0.93 0.95 0.05 932.00

Life Expectancy How can we test whether health issues influence survivorship, or if there is a difference between males and females? The amount of time one is expected to live once age class x is reached or during a specified period of time.

Use your lab sections’ data: Compute life expectancies for all age groups and for childbearing years. Do this for Males, Females, and Totals Compute life expectancies for the older cemetery and the younger cemetery. You will have 8 life ex values

Survivorship curves: Make 2: your data (Male vs. Female)
previous data (Old vs. New) BRB R.I.P.

Chi Square tests How do we know if 2 survivorship curves differ?
1) look at the graphs 2) do a 2 test We’ll use Females as our observed group and males plus females/2 as expected. Old vs. new

Graph dx for males vs. females and old vs. new. What does this tell us?

A lot of data… To leave today you need
1) Three life tables (male, female, all) using lab section’s data 2) Eight life expectancies 3) Survivorship curve (M and F) (lab section data) 4) Survivorship curve (Old and New) (Previous Data) 5) dx graphs 6) Two Chi square tests: Old vs. New (Previous data), M vs. F (lab section’s data)