Carrot, Stick or Nudges: Testing the effectiveness of Plastic Bag Compliance Behavior in Islamabad, Pakistan

Last registered on January 31, 2024


Trial Information

General Information

Carrot, Stick or Nudges: Testing the effectiveness of Plastic Bag Compliance Behavior in Islamabad, Pakistan
Initial registration date
January 28, 2024

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
January 31, 2024, 11:55 AM EST

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



Primary Investigator

COMSATS University Islamabad

Other Primary Investigator(s)

PI Affiliation
COMSATS University Islamabad, Lahore Campus
PI Affiliation
COMSATS University Islamabad, Lahore Campus

Additional Trial Information

On going
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
The use of plastic bags is one of the major urban planning challenges in Pakistan. Despite the ban in few locations in Pakistan, the consumption of single-use plastic bags is still widespread. Existing evidence suggests that monitoring and enforcement generate deterrence effects, but there are limits to such deterrence, and deterrence itself cannot fully explain all patterns of compliance behavior. Further research is needed to identify additional tools to ensure compliance with environmental regulations.

Shaping the compliance behavior needs both regulatory measures and more innovative information-dissemination-based approaches. One such approach is nudging --- a promising new policy tool, which is relatively less costly, less aggressive, and more effective. The literal meaning of nudging is to coax or gently encourage someone to do something. Nudge interventions can be very effective in an environment of weak enforcement of laws (as is generally the case in Pakistan), which explains why many governments have turned to nudge policy to influence people’s behavior. However, little is known about how to nudge environmental behavior, specifically, how to influence plastic bag consumption behavior in the retail markets in Pakistan.

The scarcity of evidence on the relative effectiveness of enforcement and nudge approaches requires an analysis of the relative effectiveness of the enforcement measures and environmental nudges in generating plastic bag compliance behavior in Pakistan. To ensure that our proposed research is aligned with the best environmental practices and has maximum policy impact, we shall partner with the Environmental Protection Agency (EPA-PAK), Sustainable Development Policy Institute (SDPI), and World-Wide Fund for Nature (WWF). We shall measure the effectiveness of a series of policy interventions (regulations and nudges) on the compliance behavior of retailers in Islamabad, Pakistan. The investigation will also focus on the longitudinal aspect of the interventions. We shall analyze how long the impact of enforcement and environmental nudges lasts. We expect our experiment to reveal the extent to which sanctions and nudges affect compliance behavior. The study results will provide guidelines to the regulators to improve plastic bag users’ compliance behavior. Generating evidence regarding the effect of creating a norm in an environment of weak enforcement will be the most important contribution of this study.

The project is expected to shape environmentally sustainable behavior, facilitate the implementation of public policies, and suggest an optimal degree of enforcement and nudging to achieve required compliance behavior. The mix of academic and policy-related expertise of the research team is expected to make the proposed study technically rigorous and relevant to national needs. The project also addresses relevant considerations, especially related to sectoral collaborations and methodological ones and suggests a methodology that should yield policy relevant information. It will also help generalize the finding in other areas of Pakistan. For instance, involving the Environmental Protection Agency, SDPI, and international stakeholders such as WWF in the current project will ensure that the project’s objectives align with the national environmental policies and are informed by best practices in the developed world.
External Link(s)

Registration Citation

Amir-ud-Din, Rafi, Rao Muhammad Atif and Muhammad Khan. 2024. "Carrot, Stick or Nudges: Testing the effectiveness of Plastic Bag Compliance Behavior in Islamabad, Pakistan." AEA RCT Registry. January 31.
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Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
The key outcome variables of interest in this experiment are the percentage of customers leaving a store with a plastic shopping bag (PBit), and the change in this percentage over time due to various interventions.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The experimental design includes three main treatments: enforcement through fines (weak and strong), information-based nudges, and a combination of both. The weak enforcement involves fortnightly monitoring, while strong enforcement includes weekly visits. Information nudges use religious and environmental texts. The combined approach merges enforcement with information nudges. The study uses a longitudinal cluster randomized control trial in urban and rural Islamabad, with data collected in three waves post-intervention. The effects of these interventions on plastic bag use are analyzed using regression models, accounting for various confounding factors.
Experimental Design Details
Not available
Randomization Method
In the experiment, a computer-generated method using the rand() command in Excel was employed to randomly select six markets in each zone. This method ensures a randomized and unbiased selection of markets for the various treatments and control groups, essential for the integrity and validity of the experimental results.
Randomization Unit
The units of randomization are retail markets within different zones of Islamabad. Specifically, six markets in each zone are randomly selected using a computer-generated method for various treatments and control groups. This cluster-level randomization ensures that the interventions are applied to groups of retail stores within each market, rather than individual stores or other entities.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
18 markets
Sample size: planned number of observations
395 retailers
Sample size (or number of clusters) by treatment arms
In the experimental design, the sample size or number of clusters by treatment arms is distributed across different market zones in Islamabad. Each treatment arm, including weak enforcement treatment, strong enforcement treatment, nudge intervention treatment, combined weak enforcement and nudge intervention treatment, and combined strong enforcement and nudge intervention treatment, is allocated to one market in each zone. With multiple zones, this results in several clusters for each treatment arm. Each market represents a cluster, and within each market, a specific treatment is implemented.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Accounting for sample design and clustering, the minimum detectable effect size for the main outcome of plastic bag usage is approximately an 8 percentage point reduction. This is based on a sample of 395 retailers divided into 18 markets with an average of 22 stores per market (cluster). With an assumed intraclass correlation of 0.05 to account for correlation in plastic bag usage within markets, 80% power, 5% significance level, and an estimated standard deviation of 20 percentage points in plastic bag usage across stores, we will be able to detect a difference of 8 percentage points or more in the plastic bag usage rate between the intervention and control groups. In other words, the interventions would need to reduce the percentage of customers using plastic bags by 8 points or more in order to be detected with adequate power given the sample size, number of clusters, and variability in the outcome.

Institutional Review Boards (IRBs)

IRB Name
Departmental Academic Review Committee (DARC), Department of Economics, COMSATS University Islamabad, Lahore Campus, Pakistan
IRB Approval Date
IRB Approval Number