Combining nudging and price incentives to promote climate friendly food consumption

Last registered on April 17, 2024

Pre-Trial

Trial Information

General Information

Title
Combining nudging and price incentives to promote climate friendly food consumption
RCT ID
AEARCTR-0013228
Initial registration date
April 08, 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
April 16, 2024, 1:06 PM EDT

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

Last updated
April 17, 2024, 2:05 AM EDT

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Region

Primary Investigator

Affiliation
CICERO Center for International Climate Research

Other Primary Investigator(s)

PI Affiliation
CICERO Center for International Climate Research
PI Affiliation
CICERO Center for International Climate Research
PI Affiliation
Norwegian University of Life Sciences
PI Affiliation
Norwegian University of Life Sciences

Additional Trial Information

Status
In development
Start date
2024-04-18
End date
2024-12-31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
In the current nudging literature, several have called for more research on the combination of behavioral interventions as a promising avenue to see larger effects (Nisa et al., 2019), and it has also been claimed that combinations of nudges and monetary interventions may be particularly effective in promoting pro-environmental behavior (see e.g. Alt et al., 2024). Most of the research on policy mixes has been done in the energy domain (Allcott et al., 2014; Drews et al., 2020; Fanghella et al., 2021) and there is a lack of research on policy mixes in the food domain. Furthermore, the existing research on policy mixing in the food domain mainly focuses on promoting healthy food products (Ahn & Lusk, 2021; Papoutsi et al., 2015; Vo et al., 2022). The purpose of this study is, first, to investigate the effect of combining a climate label on food with a climate rebate, and second, to examine how effects of each incentive individually and in combination interact with personal norms for climate friendly behavior. We contribute to the literature on incentives to promote climate friendly food consumption by combining a positive incentive with a positive label. Both the label and the price reduction presentation are developed in cooperating with an online food retailer to increase the realism of the choice tasks. The motivation for focusing on strategies that can be implemented by an online supermarket is to increase the relevance and realism of the choice experiment, since national level policies to reduce emissions from food production through reducing demand for meat are not currently politically feasible in Norway (see e.g. Larsson and Vik, 2023). However, the design is still relevant for understanding the potential effects of government policies, such as mandatory climate labels, or subsidies for less emission intensive foods. An important contribution will be to investigate synergies between financial incentives and food labeling.
External Link(s)

Registration Citation

Citation
Aasen, Marianne et al. 2024. "Combining nudging and price incentives to promote climate friendly food consumption." AEA RCT Registry. April 17. https://doi.org/10.1257/rct.13228-1.2
Experimental Details

Interventions

Intervention(s)
Respondents in an online survey (a subset of a larger number of respondents from CICEROs climate survey) will be asked to complete choice tasks where they choose between five different mince products; beef, chicken, pork, plant based, or 50/50 beef/plant based. Respondents can also choose not to purchase any of the products. The respondents are divided into four equally sized groups (one control and three treatment groups).
Treatment 1: Climate label on the plant based mince
Treatment 2: 15 % price promotion on the plant based mince
Treatment 3: Climate label + 15 % price promotion on the plant based mince
Control: No label or promotion
Intervention (Hidden)
The climate label and price promotion are designed in collaboration with the online retailer Oda, which is the largest Norwegian online grocery retailer. The products available in the choice tasks represent most minced meat products and alternatives available in Norwegian supermarkets in order to keep the choice situation as realistic as possible. We keep the product origin (Norway) fixed across all products to avoid any effects of country of origin on product choice, and the plant based protein sources are peas and fava beans, which can both be cultivated in Norway.

Treatment 1: Climate label
The climate label is presented as a green “pill” with the text “climate-friendly”, placed under the product name, next to the product picture. The placement was chosen because this is the area where information about the product is normally placed in the online store (the Oda app). The combination of placement and color makes the label quite salient, but more subtle than other attributes that normally will be of higher priority to the retailer and customer, such as price promotions or availability information. The plant based mince is the only option that is labelled as climate-friendly. This is because it is the only product with a climate footprint below the threshold of 4 kg CO2 eqv/kg product, which is the threshold for green label in Edenbrandt and Lagerkvist (2021), and is also in line with Oda’s existing classification of climate friendly recipes. To make the choice setting as realistic as possible, we do not include any further information about the climate label prior to the choice tasks, since this may make the label more salient than in a real setting. In the Oda app, it is not possible to click on labels, such as "organic" or "Nyt Norge" (a country of origin label for Norwegian sourced foods) to get more information, and we have kept this design in our experiment.

In the climate labeling literature, much of the effect tends to come from negative labels (or the red color in a “traffick light” style label) (Taufique et al, 2022). However, there are, to our knowledge, no examples of “negative” labeling of climate intensive options (red meat) being implemented in scale in a large food retailer. This could be because retailers are concerned with alienating customers, who might respond by taking their business elsewhere. A label on all products also introduces more complexity in terms of data availability to assess sustainability. To make the label more realistic, we have therefore chosen a label highlighting only the low emission alternative. Furthermore, it is interesting to study to what degree customers can be nudged to choose the most climate friendly alternative, most likely requiring a bigger leap than switching between animal proteins with different emission intensity.

Treatment 2: The rebate
The rebate is presented in the top left corner of the product image as a red circle with the rebate percentage in white. The rebate is fixed at 15 % and only applies to the plant based mince. This corresponds to the VAT on food products in Norway, and a removal of VAT for certain products, such as fruits and vegetables, has been proposed as a possible policy to promote sustainable (and healthy) food products (e.g. in the Green Party alternative budget for 2024). Fixing the rebate at this level therefore makes the results more interesting from a policy perspective. The new, rebated price is also presented with a red color, next to the crossed-out original price in grey. The rebate is implemented in such a way that the rebate is subtracted from the randomized prices in the choice experiment design.

Treatment 3: The label – price combination
In the combined treatment, the climate friendly option is presented both with a climate label and with a rebate label with new prices

Control: The control group undertakes the choice tasks without any label or rebates.
Intervention Start Date
2024-04-18
Intervention End Date
2024-05-26

Primary Outcomes

Primary Outcomes (end points)
Our main outcome variable is the sequence of product choices made by each individual in the six choice tasks, and our outcome of interest is the probability of choosing the plant based mince alternative.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Our study is a choice experiment with a d-efficient design where respondents choose between five products and a "no purchase" option. Product prices for each mince product vary at five levels; market price / 80 % of market price, 90 % of market price / 110 % of market price / 120 % of market price. Price is the only varying attribute in the choice experiment. The market price is a mean price of prices of each product collected from the online grocery store and physical supermarkets in February 2024. The design was results in 40 choice cards. Respondents are presented with six choice cards, chosen randomly from the total sample of 40 cards. The choice alternatives in each choice card are presented in random order (except opt-out which is always last).

The interventions are varied between-subject. Respondents are divided into four groups of equal size (one control, three treatment groups), and the sample of choice cards varies between the treatment groups and the control group as described above.


Experimental Design Details
Randomization Method
The randomization into three treatment groups and a control group is done by the survey company Verian. We will check that the randomization has been implemented correctly by conducting balance checks for observable characteristics of the respondents such as age and gender, and previous experience with online grocery shopping (number of times the respondent has previously shopped in online supermarket).
Randomization Unit
Randomization at the respondent level
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
0
Sample size: planned number of observations
2000
Sample size (or number of clusters) by treatment arms
500
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
The minimum detectable effect size is 0.0595 (difference in proportion) for a two-sample proportions test with an assumed control group proportion of 0.1, at power of 80 % and significance level of 5 %.
IRB

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number
Analysis Plan

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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