Synthetic control methods are a novel approach to comparative case study research using
observational data. Though developed within political science, the methods can potentially
be applied to a wide range of evaluation problems in economics, public health, social policy
and other disciplines.
In the traditional approach, an area in which a new or redesigned service is being
implemented is compared with another ‘control’ area (in which there is no change) and
statistical adjustment used to account for any differences between areas that might bias the
comparison. In the new approach, a synthetic control is derived using data on past trends in
all potentially comparable areas, providing a more robust basis for identifying the impact of
the service change.
Synthetic control methods may be a valuable addition to the range of techniques available
for non-randomised evaluations of social, economic and public health interventions. To date
there have been few applications in a UK context, and none in Scotland. Published evidence
suggests considerable potential to apply synthetic controls to public service innovations at
NHS Board, local authority or Community Planning Partnership level, and may widen the
range of policy and practice changes that can usefully be evaluated
