Two field experiments on the effectiveness of behavioral nudges to reduce plastic bag consumption.

Last registered on August 09, 2022

Pre-Trial

Trial Information

General Information

Title
Two field experiments on the effectiveness of behavioral nudges to reduce plastic bag consumption.
RCT ID
AEARCTR-0009763
Initial registration date
August 04, 2022

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
August 09, 2022, 4:32 PM EDT

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

Locations

Region

Primary Investigator

Affiliation
University of Rhode Island

Other Primary Investigator(s)

PI Affiliation
University of Rhode Island

Additional Trial Information

Status
On going
Start date
2022-08-01
End date
2022-09-15
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Single-use plastics are a ubiquitous and continuous threat to the environment—especially single-use plastic bags from everyday shopping, which people throw away after use. About 5 trillion plastic bags are used yearly worldwide, and this consumption is primarily attributed to consumer behavior. Unlike plastic food packaging, consumers can choose whether or not to use plastic bags to carry their goods from the shop to home. Through two pilot field experiments, we will test the efficacy of behavioral nudges to reduce plastic bag use among retail consumers in a developing country context. We hypothesize that consumer behavior changes towards reduced plastic bag consumption through changes in the shopping environment and giving a mild reminder to the consumers.

The first pilot experiment tests different choice conditions, where consumers shopping at a shop are asked to choose whether or not to use a plastic bag in different ways. We will create three treatment conditions and control through cluster randomization where each shop in the retail market is the unit of randomization. In the second experiment, we will test the efficacy of reminder messages written on a shopping voucher card. Another treatment arm will combine these messages with the endowment of reusable bags. Unlike the first experiment, treatment will be randomized at the individual consumer level. We expect a 15-20 percent reduction in plastic bag use among retail consumers after the end of the experiment.
External Link(s)

Registration Citation

Citation
Hasan, Tahsin and Emi Uchida. 2022. "Two field experiments on the effectiveness of behavioral nudges to reduce plastic bag consumption.." AEA RCT Registry. August 09. https://doi.org/10.1257/rct.9763
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Experimental Details

Interventions

Intervention(s)
The first experiment will test different ways of asking individuals to actively choose to engage in behavior that can be damaging to the environment. In the literature, this is termed an "active and enhanced active choice" environment. In the context of this experiment, the shop owner will give the customer the option to choose to get a plastic bag, which will be phrased in different ways, reflecting the degree of active choice and the saliency between the use of plastic bags and its impact on the environment. Three treatments will include 1) opt-in, 2) active choice, and 3) enhanced active choice.

The second experiment will test the efficacy of reminder messages to bring a reusable bag(s), and the provision of a reusable bag. Theoretically, a reminder nudge falls between cognitive and moral nudges, and it increases an individual's attention to a decision and reduces forgetfulness (Carlsson et al., 2020). Nevertheless, a reminder can bring a moral cost if it draws attention to a decision that the decision-maker eschews (Damgaard & Gravert, 2018). For example, being reminded about a task can invoke guilt in a person. However, Sunstein (2017) pointed out that a reminder may fail to change behavior if it is long and poorly worded, but it can succeed if it is short and straightforward. This experiment involves two treatments, one receiving reminder messages and a second treatment receiving reminder messages and a reusable bag.
Intervention Start Date
2022-08-05
Intervention End Date
2022-09-15

Primary Outcomes

Primary Outcomes (end points)
For the first experiment, we are primarily interested in two outcomes.
1. A binary outcome of whether a customer takes a plastic bag or not during shopping.
2. The total number of plastic bags customers take at each store.

For our second experiment, the outcome is the number of plastic bags each participating customer took during the duration of the experiment.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Experiment #1
We will use a two-level cluster-randomized trial. Shop owners will be recruited for the study, and the treatments will be randomized among the recruited shops. The treatments will be conveyed using signage at the registrars. Participating shop owners will be trained to initiate a conversation with each customer to direct their attention to the signage in front of the cash register. We will observe individual transactions and conduct customer surveys with a subset of the customers. The enumerators will stand at a position where they can observe and record three items for each customer: (1) whether or not the consumer took a plastic bag and, if so, how many?, (2) the amount of transaction, and (3) did the consumer bring any bag. This survey will collect information on other covariates necessary for the statistical analysis of the treatment effect.

Experiment #2
We will use a multi-site blocked randomized controlled trial with individual-level treatment randomization. Shops will be recruited in different areas (blocks) to participate in the study. During the experiment, we will approach every other individual who shops in those stores to participate in a consumer survey. After getting the consent for participation from the customer, the enumerator will give the customer a shopping voucher card. The voucher will carry a monetary value for all participants. In one treatment, randomly selected customers will receive vouchers with reminder messages; in a second treatment, customers will receive the messages along with a reusable bag for future use.
Experimental Design Details
Experiment #1
We will use a two-level cluster-randomized trial. First, we will recruit shops in the bazaars where shop owners will be offered compensation for participation in the study. Second, we will randomize the treatment among the recruited shops. We will observe individual transactions and conduct consumer surveys from the participating shops. We will apply the treatment through simple signage installed in front of the cash register in the shop. Participating shop owners will also be trained to initiate a conversation with consumers to direct their attention to the signage in front of the cash register. The intervention will continue for a week at each shop. For logistical considerations, we will rotate shops into treatments in a randomized order over four different weeks.
We will collect two types of data: a) we will observe individual customers' choices during a shop transaction. Our enumerators will stand by in a position where they can observe three things (1) whether or not the consumer took a plastic bag and, if so, how many?, (2) the amount of transaction, and (3) did the consumer bring any bag; b) we will conduct consumer surveys for every nth person shopping in that shop depending on the number of customers come in every hour; b) the survey will collect information on other covariates necessary for the statistical analysis of the treatment effect.

Experiment #2
We will use a multi-site blocked randomized controlled trial with individual-level treatment randomization. First, we will approach individual shops in different areas (blocks) to participate in the study and offer participation incentives to the shop owners. Next, we will approach every other customer who shops in those shops to participate in a customer survey. We will inform participating customers that we are surveying what items the customer buys from this shop for the next three weeks. After getting the consent for participation from the customer, the enumerator will give the customer a shopping voucher card. The voucher will carry a monetary value for all participants. In one treatment, randomly selected customers will receive vouchers with reminder messages; in a second treatment, customers will receive the messages along with a pair of reusable bags for future use. The participating customers will be told they can redeem the value of the products using the voucher card if they shop from this shop within the next three weeks at least three times. The other condition is that no other person in the household can redeem the value except the participating customer. The shopping voucher card is a direct incentive for participation for the customers.
Randomization Method
Experiment #1: Cluster randomization using individual stores as clusters
Experiment #2: a multi-site blocked randomized controlled trial with individual-level treatment randomization.
Randomization Unit
Experiment #1: Shops
Experiment #2: individual customers
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
Experiment #1: 40 retail shops from five different local markets in Dhaka
Experiment #2: 15 shops in three different local markets in Dhaka
Sample size: planned number of observations
Experiment #1: 400 customer surveys from 40 clusters and at least 100 observational data from each cluster Experiment #2: 120 customer surveys
Sample size (or number of clusters) by treatment arms
Experiment #1: 10 clusters per treatment arm. (three treatments and a control)
Experiment #2: 40 individuals under each treatment arm (two treatments and control)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We expect a 15-20% reduction in plastic bag use among the retail customers under the treatment conditions compared to the control group.
IRB

Institutional Review Boards (IRBs)

IRB Name
University of Rhode Island, IRB
IRB Approval Date
2022-07-05
IRB Approval Number
1927161-1

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials