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Table 12.3

Studies that use DD

Study

Outcome

Treatment

Treated/controls

Comments

Adams (2007)

Relative wages for olderworkers

Introduction of purecommunity rating amongsmall group health insurersin New York in 1993

(i) Data for small and largefirms in New York only: timeinteracted with olderworkers and employment insmall firm(ii) Data for small firms in allstates: time interacted witholder workers and New York

Uses two sets of DDDestimates. Finds an increasein relative wages of olderworkers in small firms

Carpenter (2004)

Self-reported alcohol use anddrunk driving

Zero tolerance drunk drivinglaws

In DDD estimators zerotolerance laws interactedwith age 18–20, the groupaffected by the laws, and age22–24

Finds an effect on episodicdrinking among males, butfor other outcomes

Chalkley andTilley (2006)

Intensity of dental treatment Remuneration of dentists,

FFS or salary

Interacts salaried versusself-employed dentists withexempt versus non-exemptpatients

Find that self-employeddentists treat exemptpatients more intensively

Chen

et al

. (2007)

Use of outpatient andinpatient care and healthstatus among the elderly

Introduction of NHI inTaiwan in 1995

Those who became insuredunder NHI/those alreadyinsured

Find an impact on use ofcare, which is larger forthose on low incomes, butnot on health

Chen and Zhou(2007)

Height, labor supply,earnings

1959–61 famine in China

Birth cohorts interacted withregional differences inseverity of famine (proxiedby excess mortality)

Find worse outcomes forthose exposed to the famine

Cockx andBrasseur (2003)

Demand for physicianservices

Increase in co-payments

Non-exempt/exempt

DD applied to a Rotterdamdemand system

Continued