Part of: Closed coffeeshop chain experiment
Independent evaluation
The scientific research is carried out by an independent team, supervised by a Guidance and Evaluation Committee of professors and experts. The baseline measurement took place from September 2021 to April 2022; together with a zero-measurement in 2022 it forms the basis for further evaluation.
Research design
Quasi-experimental design comparing ten intervention municipalities with nine control municipalities. The intervention municipalities run the experiment; the control municipalities continue under the regular tolerance policy.
Control municipalities
- Enschede — compared with Almere
- Helmond — compared with Heerlen
- Leeuwarden — compared with Groningen
- Leiden — compared with Nijmegen
- Lelystad — compared with Zaanstad
- Roermond — compared with Maastricht
- Tiel — compared with Arnhem
- Utrecht — compared with Breda
- Zutphen — compared with Hellevoetsluis / Voorne aan Zee
Matched on size, number of coffeeshops, socio-demographic characteristics and geographical location — so that measured differences can be attributed to the experiment rather than to external variables.
Research questions
- Effects on public health (purer products, information).
- Effects on crime and nuisance (reduction in illegal trade).
- Economic viability for growers, distribution and coffeeshops.
- The extent to which consumers shift from illegal to regulated.
- Effectiveness of the track & trace system and the closed chain.
Methods
- Interviews with around 130 stakeholders (municipalities, police, justice, operators).
- Visits to 142 coffeeshops, counting 1,252 visitors.
- Surveys among 922 visitors, residents and staff.
- Analysis of menus and periodic measurements.
More information
The full WODC report (summary, PDF): Research closed coffeeshop chain experiment — summary.