Using natural experiments to improve public health evidence: a review of context and utility for obesity prevention

Table 2 Summary of study characteristics

Classification	Sub-classification	N
Intervention characteristics		46
Intervention setting	Policy intervention	19
	Environmental intervention	17
	Community intervention	5
	Individual behaviour intervention	1
	Economic intervention	2
	Migration	2
Scale of intervention	National	8
	State/region	12
	City/neighbourhood	26
Intervention theme	Food labelling	4
	Food regulation/taxation	3
	Food accessibility	6
	Workplace/school/community physical activity programme	7
	Built infrastructure development	11
	Transport interventions	4
	Social environment changes	3
	Clinical/screening procedure	2
	Economic events	4
	Other	2
Evaluation characteristics
Study design	Longitudinal pre/post quasi-experiment	15
	Longitudinal pre/post cohort (single group)	6
	Interrupted time series	4
	Repeat cross-sectional surveys	9
	Post-test observation only	9
	Qualitative only	2
	Pre-test observation only	2
Data source	Primary	27
	Secondary	15
	Mixed	4
Data collection^a	Short-term (<3 years)	21
	Long-term (3+ years)	12

ISSN: 1478-4505