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Effect of extended trading hours on alcohol sales in Norway: a cluster randomised controlled trial
Last registered on September 01, 2020

Pre-Trial

Trial Information
General Information
Title
Effect of extended trading hours on alcohol sales in Norway: a cluster randomised controlled trial
RCT ID
AEARCTR-0006290
Initial registration date
August 18, 2020
Last updated
September 01, 2020 3:57 AM EDT
Location(s)
Region
Primary Investigator
Affiliation
Norwegian Institute of Public Health
Other Primary Investigator(s)
PI Affiliation
Norwegian Institute of Public Health
PI Affiliation
Norwegian Institute of Public Health
Additional Trial Information
Status
On going
Start date
2020-09-01
End date
2023-12-31
Secondary IDs
Abstract
Introduction: Norwegian alcohol policy measures include national restrictions on sales hours and a state monopoly on retail sales of strong beer, wine and spirits. Medium strength beer is sold in licensed grocery stores.
A one-hour extension of sales hours per week in the monopoly outlets can take effect from September 1st 2020. The Norwegian Ministry of Health and Care requested the Norwegian Institute of Public Health to evaluate possible effects of this change.
We aim to evaluate whether this increase in sales hours results in 1) an increase in alcohol sales in the monopoly outlets, and 2) an increase in total alcohol sales, including possible substitution effects from beer sales in grocery stores.

Design and methods: The state monopoly has agreed to implement extension of sales hours within a cluster randomised controlled trial design, to render possible an effect evaluation of this policy change. The unit of randomisation is trade district (total n=67 in Norway). Block randomisation of 62 of the 67 trade districts will allocate monopoly outlets to one of three experimental conditions regarding date of implementation of extended trading hours; i) September 1st 2020; ii) December 1st 2020, and iii) March 1st 2021. The extension of sales hours will be from 3 pm to 4 pm on Saturdays. Data on monthly sales of alcohol (total and beverage specific) in all monopoly outlets and grocery stores in Norway Norway will be obtained for a period of 72 months prior to – and 24 months after – implementation (i.e. from September 1st 2014 to March 1st 2023). Simulations suggest an increase in wine sales of 3.5%, which would be statistically significant under reasonable assumptions of power and analysis model.

Conclusion: The planned randomised controlled trial offers a rare opportunity to study possible causal effects of a relatively small change in a widely used alcohol policy measure.
External Link(s)
Registration Citation
Citation
Rossow, Ingeborg, Daniel Bergsvik and Maja Weemes Grøtting. 2020. "Effect of extended trading hours on alcohol sales in Norway: a cluster randomised controlled trial ." AEA RCT Registry. September 01. https://doi.org/10.1257/rct.6290-2.2.
Sponsors & Partners
Sponsor(s)
Experimental Details
Interventions
Intervention(s)
A one hour extension of trading hours on Saturdays in state alcohol monopoly outlets.
Intervention Start Date
2020-09-01
Intervention End Date
2021-03-01
Primary Outcomes
Primary Outcomes (end points)
Key outcome variables are monthly alcohol sales (total and beverage specific) in monopoly outlets and in licensed grocery stores, both measured in beverage specific volumes and in litres of pure alcohol.
Primary Outcomes (explanation)
Data on alcohol sales are provided in litres per beverage category, which will be calculated into litres of pure alcohol. All variables will be adjusted for seasonal variation.
Secondary Outcomes
Secondary Outcomes (end points)
i) Weekly alcohol sales (total and beverage specific) in monopoly outlets and in licensed grocery stores ii) distribution of total alcohol sales over days of the week (Monday through Saturday) in monopoly outlets; iii) distribution of alcohol sales over the trading hours on Saturdays in monopoly outlets, as measured in litres of pure alcohol and beverage specific volumes; iv) monthly alcohol sales (total and beverage specific) in monopoly outlets, as measured in turnover (NOK).
Secondary Outcomes (explanation)
Data on alcohol sales are provided in litres per beverage category, which will be calculated into litres of pure alcohol. All variables will be adjusted for seasonal variation.
Experimental Design
Experimental Design
A cluster randomised controlled trial design will be applied, using trade districts as clusters for randomisation.
Experimental Design Details
Not available
Randomization Method
In office by a computer running a STATA block randomisation algorithm
Randomization Unit
Trade district
Was the treatment clustered?
Yes
Experiment Characteristics
Sample size: planned number of clusters
62 trade districts
Sample size: planned number of observations
228 monopoly outlets included in experimental design
Sample size (or number of clusters) by treatment arms
21 trade districts implement extended trading hours September 1st 2020; 21 trade districts implement extended trading hours December 1st 2020; and 20 trade districts implement extended trading hours March 1st 2021.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Power calculations were conducted as follows. Simulations were performed employing real sales data from January 2014 to August 2019. In these simulations, we assumed that extended opening hours were implemented by trade districts from September 1st 2018, December 1st 2018, and March 1st 2019, thus resembling the dates of the planned experiment, only two years before. For each outlet, the predicted increase in sales was set to be a uniformly distributed rate over the interval (0, 0.3) of mean hourly sales on Saturday afternoons in 2018; and this effect was further weighted by a relative measure of increasing sales on Saturday afternoons as compared to sales in the morning hours. The simulated increase in sales on Saturdays, given a one hour increase in trading hours, was then added to monthly sales data on which we ran regressions with standard errors adjusted for clustering. In the regression models, we also accounted for seasonal variation. With 100 simulations of different block randomisations and random effect sizes, we were unable to produce parameter estimates for wine (mean β=0.030) and spirits (mean β=0.025)  which were not statistically significant at p< 0.05. However, the effect on beer sales (mean β=0.018) was mostly statistically insignificant.
Supporting Documents and Materials

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Documents
Document Name
WHO Dataset
Document Type
other
Document Description
Short description of study protocol applying the WHO registration form for trial registration.
File
WHO Dataset

MD5: 7161d95e9f3a778a73f3066372d98bb1

SHA1: e44287348dd6f88f43e33e7d637ff8b7b51d6a7d

Uploaded At: August 31, 2020

IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
IRB Approval Date
IRB Approval Number
Analysis Plan
Analysis Plan Documents
Analysis Plan

MD5: 3c10101d513c8f772cfbef1179d505ee

SHA1: 790da89cb00316ac018803a27f718e887cf07f81

Uploaded At: August 31, 2020

Timeline Diagram

MD5: 4a435999b9ad8970c23ddf05d0b3e9f0

SHA1: e0d4950fee3cbfe71f619ef339e8d32ef11c0ba9

Uploaded At: August 31, 2020