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Making Sense of Sorting
Last registered on March 23, 2019
View Trial History
Making Sense of Sorting
Initial registration date
March 22, 2019
March 23, 2019 8:29 PM EDT
Simon Birk Nielsen
University of Copenhagen
Contact Primary Investigator
Other Primary Investigator(s)
Anders Adser Sørensen
Additional Trial Information
Environment & Energy
A field experiment seeking to improve the waste sorting among urban households living in apartment buildings in the municipality of Copenhagen. The study will focus on bio waste and use general waste as an indicator of the general level of waste sorting.
The field experiment takes place over a 9-week period within 5 yards, covering around 900 households.
A treatment group will receive a postcard with information regarding the positive effects of waste sorting (information-based instruments) as well as a sticker reminding the subjects to sort their waste (implementation intentions). In the treatment yards, stickers will be placed on all bio and general waste bins, providing feedback to the households of the current sorting levels compared to the average of the neighbourhood using both descriptive and injunctive messages (social norms). These stickers will be updated with new numbers three weeks after the first implementation. A control group will only be observed.
We expect to observe an increase in the amount of bio waste sorted as well as a decrease in the level of general waste, as treated households engage in waste sorting of not only bio waste but other fractions as well, i.e. plastic, metal, paper etc.. The control group is expected to have a relatively constant level of waste sorting.
Adser Sørensen, Anders and Simon Birk Nielsen. 2019. "Making Sense of Sorting." AEA RCT Registry. March 23.
Adser Sørensen, Anders, Simon Birk Nielsen and Simon Birk Nielsen. 2019. "Making Sense of Sorting." AEA RCT Registry. March 23.
Sponsors & Partners
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
Volume of bio waste and general waste
Primary Outcomes (explanation)
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
The field experiment will be conducted in 5 yards across the municipality of Copenhagen for 9 weeks, covering a total of around 900 households in apartment buildings. The yards have been chosen according to when the trans bins are being emptied by the municipality. Having bio waste and general waste emptied the same day ensures precise measurements while making it possible to compare the different years. This requirement has therefore been the determining factor when choosing which yards to include in the field experiment. Alas, the selection of the 5 yards is assumed to be random.
The yards have been assigned to a treatment and control group according to geographical factors making sure that the amount of observations (number of bio and general waste bins as well as number of households expected to use the sorting stations) is the same across the two groups.
The treatment group will receive a postcard with information regarding the positive effects of sorting waste (information-based instrument) as well as a sticker intended to be used to remind themselves to sort their waste (implementation intention). Furthermore, a sticker will be placed on all bio and general waste bins in the yards, informing the households of their current level of sorting compared to the average of the neighbourhood as a whole using both descriptive and injunctive messages (social norms). After three weeks, these stickers will be updated with new averages, giving the households feedback on their progression.
The field experiment will take place over 9-10 weeks where measurements will be take twice a week (general waste is collected twice, bio waste only once).
The first three weeks will serve as a baseline. Then the intervention described above will be implemented followed by three more weeks of measurements. Hereafter, the stickers on the waste bins will be updated, and we will measure for three more weeks.
Experimental Design Details
Randomization of sample size is done according to the municipality's official plan covering which trash bins are emptied when.
Randomization between control and treatment is done based on geographical factors.
Was the treatment clustered?
Sample size: planned number of clusters
5 yards with a total of 21 sorting stations, each containing several waste bins
Sample size: planned number of observations
21 sorting stations covering 32 bio waste bins and 78 general waste bins
Sample size (or number of clusters) by treatment arms
3 yards control (12 sorting stations), 2 yards treatment (9 sorting stations)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Approval Date
IRB Approval Number
Post Trial Information
Is the intervention completed?
Is data collection complete?
Is public data available?
Reports, Papers & Other Materials
REPORTS & OTHER MATERIALS