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Norm-based feedback on household waste recycling: a field experiment
Last registered on December 03, 2019

Pre-Trial

Trial Information
General Information
Title
Norm-based feedback on household waste recycling: a field experiment
RCT ID
AEARCTR-0003301
Initial registration date
December 03, 2019
Last updated
December 03, 2019 11:11 AM EST
Location(s)

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Primary Investigator
Affiliation
University of Gothenburg
Other Primary Investigator(s)
PI Affiliation
University of Southern Denmark
Additional Trial Information
Status
In development
Start date
2018-05-01
End date
2020-12-31
Secondary IDs
Abstract
The last decade has seen a marked upsurge of research into ‘norm-based feedback’ interventions, which aim to reduce the consumption of some resource by providing users with information about their use compared to e.g. neighbors in their community. As far as we are aware, ours is the first study on the effect of providing such feedback within the waste domain. We run separate randomized controlled trials of accurate and household-specific norm-based feedback on residual (unsorted) waste in two municipalities in western Sweden, Partille and Varberg. In total, some 20,000 single-family households participate, about three-quarters of which are located in Varberg. Our main feedback condition, which we term “static” feedback, replicates the by now standard Opower-style norm and involves comparing each household’s own residual waste (in kilograms per person) with an average among roughly 100 nearby households. We also explore differently presented, “dynamic” feedback motivated by psychological evidence that norms focusing on changes in behavior, rather than snapshot pictures of consumption differences within a population, are more effective at reducing use.
External Link(s)
Registration Citation
Citation
Ek, Claes and Magnus Söderberg. 2019. "Norm-based feedback on household waste recycling: a field experiment." AEA RCT Registry. December 03. https://doi.org/10.1257/rct.3301-1.0.
Sponsors & Partners

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Experimental Details
Interventions
Intervention(s)
Intervention Start Date
2019-03-18
Intervention End Date
2019-10-29
Primary Outcomes
Primary Outcomes (end points)
Collected residual waste (kgs/person)
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Collected food waste (kgs). If possible, electricity use by households in Varberg
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
We run separate trials of norm-based feedback on household residual waste (the unsorted waste fraction) in two municipalities in western Sweden, Partille and Varberg. In total, some 20,000 single-family houses participate in these studies, about three-quarters of which are located in Varberg. As in previous studies, the aim of the experiment is to examine whether treated households that receive feedback reduce their generation of residual waste compared to a control group that does not receive feedback.

In both municipalities, households are divided roughly equally into three treatment arms, including a control group. However, the two treatments differ across our participant municipalities.
Experimental Design Details
Not available
Randomization Method
Random number generator.
Randomization Unit
Cluster randomization with blocking: three clusters per block. Treatment perfectly correlated within cluster. Each block/cluster is a contiguous set of households.
Was the treatment clustered?
Yes
Experiment Characteristics
Sample size: planned number of clusters
Partille: 55*3 = 165
Varberg: 172*3 = 516
Sample size: planned number of observations
Partille: 5,756 Varberg: 15,723 Due to some households opting out of the study, we expect our actual data set to cover roughly 5,000 in Partille and 15,000 in Varberg.
Sample size (or number of clusters) by treatment arms
Partille: 55 clusters/treatment arm
Varberg: 172 clusters/treatment arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Partille MDE: 0.079 kgs residual waste/person (2.378% of data average) Varberg MDE: 0.050 kgs residual waste/person (1.307% of data average) This is based on a formula for power calculation with panel data and cluster randomization. For further details on variance components, etc.: see the pre-analysis plan.
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
Department of Economics Ethics Committee
IRB Approval Date
2018-11-13
IRB Approval Number
N/A
Analysis Plan

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