A New Approach to Social Mobility Models: Simulation as “Reverse Engineering”
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Transcript of A New Approach to Social Mobility Models: Simulation as “Reverse Engineering”
A New Approach to Social Mobility Models: Simulation as “Reverse
Engineering”
Edmund Chattoe and Anthony HeathDepartment of Sociology
University of Oxford3 George Street Mews
Oxford OX1 2AAhttp://www.sociology.ox.ac.uk
Plan of the Presentation
• Why are sociologists so hard to convince about simulation?
• What is social mobility?• A description of MOBSIM• Initialising populations with structure: a
simulation puzzle
Sociology and Simulation
• Fundamental split: “qualitative” versus “quantitative” approaches
• Qualitative sociologists don’t like simulation because they don’t like any modelling
• What about quantitative sociology?• That shares a view of regularities as social
phenomena not “laws”.
“Real Problems”
• Quantitative sociologists want to study “real” problems:– Lots of data, direct and surrounding– Social institutions (schools, factories) and
social structure (family relations)– Problems set by academic consensus
(tradition) rather than choice
Two Kinds of “Theory”
MACRO MACRO MACRO
Statistical Model World Simulation
MICRO MICRO MICRO?
?
Problems with Statistical Models
• Curve fitting (rather than cross checking at different levels) is not real testing
• “Theories” of micro behaviour compatible with statistical approaches must either be very “tidy” (RCT) or run the risk that the macro behaviour emerging from it not what was anticipated
Reverse Engineering
• “Pick apart” dependent variables and set in order: the problem of “scope”
• Do “normal simulation stuff”: experiments, validation, exploring theory lacunae
• Generate original patterns (and ideally others) thus producing a simulation that is both “relevant” and falsifiable
The Scope of Models
Labour Markets
Demography
Education
??
What is Social Mobility?– Movement between classes over time:
• Inter and intra generational• Relative and absolute mobility
– Motivations for study:• Efficiency• Social Stability• Morality
– Findings• Meritocracy and myth• Comprehensive schools• Considerable constancy of ASM
MOBSIM• A microsimulation with behaviour• Initialised at “1901”• Key Features
– Identities– Classes (equated with jobs)– Education (“epoints”)– Status– “Institutions” and “Biology”– Labour market
Constructive Surprise Example• Models of more than minimal complexity
are falsifiable• People with less education can hold better
jobs• This occurs because even though hiring is
meritocratic, firing is probabilistic• Observers might attribute this to
discrimination• It also suggests new research
Distribution of Education Points By Class
0
0.5
1
1.5
2
2.5
0 200 400 600 800 1000 1200Education Points
Series1
Developing the Model• Endogenising norms• Disaggregating the school sector• Dealing with anachronisms• Disaggregating the labour market• Removing “arbitrary” parameters• Adding material resources• Adding spatial location• Adding social networks
Possible Experiments I: Cultural Shifts
• Homogamy• Women’s labour market participation
and higher education• Divorce• Birth control, demography and genetics• Deliberate policy• Ascription and meritocracy
Possible Experiments II
• Validating Statistical Assumptions– Class Aggregates– Time at Measurement– Transmission through the father
• “Exogenous” Factors– War– Sectoral Change and International Adjustment
The Problem of Structured Populations I
• Three kinds of structure– No structure: agents with separable attributes
initialised randomly– Some structure: microsimulations in which
attributes like “number of children” matter– Detailed structure: social mobility, attributes
like “my father” matter• Again an unremarked feature of these
models
The Problem of Structured Populations II
Pseudo Histories Pseudo Parents
TWO POSSIBLE SOLUTIONS
The Problem of Structured Populations III
• Pseudo Histories– Consistency of pseudo history distributions
with actual run distributions– Problem of “linking” pseudo histories to each
other• Pseudo Parents
– Hard to generate stable populations– Large “overhead” of lead time and boom and
slump in initial pseudo population
The Problem of Structured Populations IV
• Should we worry that this problem has never come up before?
• Just how much structure is plausible for real social systems?
What is Microsimulation?
• Agents and attributes• Environment and different updating rules• Initialisation