Follow-up study: Can children’s engagement in recycling processes reduce household waste?

Last registered on December 06, 2021


Trial Information

General Information

Follow-up study: Can children’s engagement in recycling processes reduce household waste?
Initial registration date
November 29, 2021

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
December 06, 2021, 2:15 PM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.


Primary Investigator

University of Gothenburg

Other Primary Investigator(s)

PI Affiliation
Halmstad University

Additional Trial Information

On going
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
This study is a follow-up to AEARCTR-0003300 ("Can children’s engagement in recycling processes reduce household waste?"). Again, we perform an educational intervention with school children aged 10-16 in two municipalities in Sweden, treating some 200 children (expected), and couple with municipal waste data to check whether the intervention impacts waste behavior in households with participating children. The new study differs from the previous one in the following ways. First, to strengthen the intervention and effectively provide additional reminders of the desirability of pro-environmental behavior, we add two additional classroom sessions to the design. Second, for similar reasons, we prolong the home assignment from seven to ten days. Third, to better integrate our intervention into existing curricula, it is now conducted by regular teaching staff rather than directly by us. Fourth, to maintain sample size, we do not randomize students into treatment and control: all participating students are treated. Identification instead uses matching and/or weighting on pre-intervention baseline data to construct a suitable control group for households with a participating student.
External Link(s)

Registration Citation

Ek, Claes and Magnus Söderberg. 2021. "Follow-up study: Can children’s engagement in recycling processes reduce household waste?." AEA RCT Registry. December 06.
Sponsors & Partners



Experimental Details


Treatment: expanded educational package on waste, administered by regular teaching staff. (i) Home assignment (weighing residual and food waste), (ii) Brief lecture, group discussion, educational game, (iii) Extended reading exercise (covering 2 hour-long sessions) on the Sustainable Development Goals.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
1) Residual waste amounts (in kilograms), 2) Food waste amounts (in kilograms)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The intervention covers no fewer than four classroom sessions, though participating teachers have discretion to add additional material. In the first session, all students are given an exercise: to measure, each day over a period of ten days, the amount of waste generated in their household or the household they are visiting that day. Between one and three weeks after the conclusion of these exercises, the second session occurs. Students then listen to a brief lecture on waste and the environment, participate in a subsequent group discussion, and finally play an educational game where they answer quiz questions on waste and tasked with correctly sorting cards representing different waste fractions. Finally, the third and fourth sessions consist of an extended reading exercise (with associated quiz questions) on the UN Sustainable Development Goals. Students may complete this exercise alone or in small groups.

As part of the initial home assignment, each student fills in a form provided by the experimenters. This is the main data source from the intervention itself. One of the fields specifies the address where, for each day, the assignment was carried out. These addresses are then combined with household-level waste data, allowing estimation of ATEs on waste amounts among households where a student was treated. The presence of (many) non-participant households in the waste data allows us to to construct a suitable non-randomized control group through matching and/or weighting (synthetic control) on pre-intervention waste amounts. The pool of potential control units for a given participant household consists of non-participant households in the same area.
Experimental Design Details
Randomization Method
In the earlier study (AEARCTR-0003300) which the present study follows, assignment of students within a given class into treatment and control was done by manual card shuffling. Assignment of experimenters to the treatment and control groups was done by coin flips. In the present study, all participating students are treated, so there is no randomization.
Randomization Unit
Quasi-experimental identification done at the household (address) level.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
200 addresses.
Sample size: planned number of observations
200 addresses.
Sample size (or number of clusters) by treatment arms
200 treated addresses. Unknown number of control addresses to be selected by matching from the pool of all households in an area around each participating household.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Previous study (with about 200 treated students) had: Residual waste: 0.68 kg (6.69%, SD = 9.49) Food waste: 0.46 kg (9.8%, SD = 6.41) Due to the similar number of treated students in the present study, it is expected to roughly match these figures.

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number


Post Trial Information

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials