WP 3 Projections of the Changing Family Unit and Kinship Structure

1
WP 3 Projections of the Changing Family Unit and
Kinship Structure

• M Murphy, LSE E Grundy, LSHTM

2
WP 3 Projections of the Changing Family Unit and
Kinship Structure

• Objective - to produce projections of the older
  population by age, sex and kinship status
• Kinship ties become more important with age, as
  kin form a major resource in times of need.
• Having kin is a precondition for kin interaction
  and support
• Cumulative lifetime experiences such as total
  number of partnerships substantially affect
  interactions with other kin.

3
WP 3 Projections of the Changing Family Unit and
Kinship Structure

• Main demographic trends of first second
  demographic transitions in now-developed
  societies
• Initially
• fertility declined from about five children per
  woman in 19th century to 'below-replacement
  level' today
• mortality has declined so that life expectancy
  doubled from 40 to 80 years over 20th Century
• populations aged so around 20 people now aged
  65
• More recently
• substantial reductions in nuptiality and
  increases in non-marital cohabitation divorce
  proportion of births outside marriage

4
WP 3 Projections of the Changing Family Unit and
Kinship Structure

• Kinship distribution is determined solely by the
  fertility, mortality, nuptiality (inc. divorce
  and cohabitation) experienced by the population
  for many decades prior to that time point
• The contemporary pattern of kinship is also
  influenced by more recent partnership trends,
  especially when step-kin are considered
• Little information available in Britain (or
  elsewhere) on kinship in large nationally-represen
  tative data sources.

5
Micro-simulation

• Micro-simulation may be used to estimate and
  project the numbers and types of kin that people
  are likely to have under various conditions.
• We start with known or assumed population of many
  individuals, and then simulate individual
  demographic events.

6
The SOCSIM Model

• Hammel Wachter (UC Berkeley)
• Monte Carlo method
• An initial population of individuals sub-divided
  by sex and age is fed to the computer, and these
  individuals age month by month Some will marry
  (or cohabit) with each other, give birth, divorce
  or remarry, and finally they die
• The occurrence of these events for each person of
  a given age, sex, marital status etc is
  determined by random numbers in with probability
  specified by the user's choice of governing
  demographic rates (i.e. produces correct
  averages)
• Model builds up kinship links for an initial
  population of unrelated and never-married people
  to any degree of complexity

7
Proportion with livingnatural parents and
children
WP 3 Projections of the Changing Family Unit and
Kinship Structure
An example people with living parents and
children, 1950, 2000 2050
8
WP 3 Projections of the Changing Family Unit and
Kinship Structure

• Family unit kinship structure linkages