Diet Improvement Through Normative Experimentation

NCT05070442 | Completed

• 1 other identifier: NIHA-2018-002 (Study 2)
• Study Type: interventional
• Target: 248
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to use a three-arm randomized control trial (RCT) implemented in a fully functional experimental online grocery store, to explore the effects of two low-cost information and incentive-based strategies. These strategies comprise of injunctive norm-based messaging and the use of financial incentive leveraging on loss aversion to encourage the purchase of healthy foods. The investigators have set up a store wherein products may be purchased by participants and subsequently delivered to homes in some of the conditions. This increases the external validity of these interventions and enables investigators to establish greater confidence in their generalizability.

Conditions

Diet Quality

Keywords

Nutri-Score labels; Social norms; Peer comparison; Financial incentives; Loss aversion; Online grocery shopping

Outcome Measures

Primary Outcomes (1)

• Diet Quality

  Diet quality, as measured by raw Nutri-Score points (-15 to 40) weighted by number of servings of all basket items. Here, a smaller value means a better outcome. Raw Nutri-Score is measured according to the guidelines from the Sante Publique France.

  After completion of data collection, an average of about 5 months

Secondary Outcomes (6)

• Average Nutri-Score

  After completion of data collection, an average of about 5 months

• Average Calories

  After completion of data collection, an average of about 5 months

• Average Sodium

  After completion of data collection, an average of about 5 months

• Average Sugar

  After completion of data collection, an average of about 5 months

• Average Fat

  After completion of data collection, an average of about 5 months

Study Arms (3)

Control Arm (Arm 1)

NO INTERVENTION

Participants will experience an unmodified version of NUSMart which replicates the traditional shopping experience of online grocery stores.

Norms Arm (Arm 2)

EXPERIMENTAL

Participants will experience a modified version of NUSMart with norm-based messaging and peer comparison features enabled. Nutri-Score labels will be enabled and displayed on all products within the store. A floating side panel will provide a visual indicator of the participants' average weighted Nutri-Score.

Behavioral: Norm-based messaging and peer comparison features

Norms and Incentive Arm (Arm 3)

EXPERIMENTAL

Same as Arm 2, except participants are notified that they have been awarded an additional $5 towards their participation reimbursement. However, this additional $5 will be forfeited if their basket average weighted Nutri-Score falls below the average of their peers'. (Financial incentive leveraging on loss aversion).

Behavioral: Norm-based messaging and peer comparison features; Behavioral: Financial Incentives leveraging on loss aversion

Interventions

Norm-based messaging and peer comparison features BEHAVIORAL

Participants are shown a version of NUSMart which includes Nutri-Score labels that are enabled and displayed besides all the products in the store. Additionally, they are shown a video that gives them background information about Nutri-Score labels and describes the following features enabled in this intervention: * Norm-based messaging will be displayed in the form of a happy or sad emoticon based on whether the participant's current basket average Nutri-Score (weighted by number of servings) is above or below "other shoppers" (Nutri-Score=3.98). * Peer comparison will be implemented as a vertical ruler display of the participant's current basket average Nutri-Score (weighted by number of servings) as well as that of their "peers". Nutri-Score=3.98 was chosen as it is 10% better than the mean Nutri-Score of baskets purchased by participants in the Nutri-Score labelled intervention arm of a prior study.

Norms Arm (Arm 2); Norms and Incentive Arm (Arm 3)

Financial Incentives leveraging on loss aversion BEHAVIORAL

Participants are informed that they have received an additional $5 towards their participant reimbursement. However, this amount will be forfeited if they check-out with a basket average Nutri-Score (weighted by the number of servings) that falls below the average Nutri-Score of "other shoppers" i.e. 3.98. An indicator on the screen that informs the participants of this potential forfeiting will be included.

Norms and Incentive Arm (Arm 3)

Eligibility Criteria

• Age: 21 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Singapore resident
• Age 21 and above
• Must be the primary weekly grocery shopper in their household

You may not qualify if:

• Non-Singapore resident
• Non-primary grocery shopper in their household
• Less than 21 years old

Sponsors & Collaborators

• Duke-NUS Graduate Medical School: lead

Study Sites (1)

Duke-NUS Graduate Medical School

Singapore, 169857, Singapore

Location

Study Officials

• Eric A Finkelstein, PhD MHA

  Duke-NUS Graduate Medical School

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: HEALTH SERVICES RESEARCH
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: September 20, 2021
• First Posted: October 7, 2021
• Study Start: April 22, 2022
• Primary Completion: October 26, 2022
• Study Completion: October 26, 2022
• Last Updated: February 15, 2023

Record last verified: 2023-02

Data Sharing

• IPD Sharing: Will not share

Locations

SG (1)