A Randomized Trial and Impact Evaluation of Singapore's New Food Labels Aimed to Address the War on Diabetes

1. Experimental Design and Procedures

The aim of this study is to use a 2 x 2 within-subject crossover design with an online grocery store, to systematically evaluate the effect of the new SSB front-of-pack labels, Nutri-Grade, on diet quality and examine how this effect varies by shoppers' income and education level. To this end, the investigators will be using two different versions of an online experimental grocery store called NUSMart, designed for research purposes. The two versions are described below. 2. Overview of Experimental Design

The investigators will recruit Singapore residents aged 21 years or older. Prospective participants will be asked to complete an online screener to determine their eligibility to participate in the study. Those who do not consent or are deemed ineligible will be notified of their ineligibility with an on-screen message.

If interested and eligible, the applicant will then be asked to complete a registration form containing name, mobile number, and email address. Contact information for the Duke-NUS study team will be provided to allow questions to be asked at any point in the consent process and throughout the study. Upon completion of the registration form, NUSMart will create the participant account and a unique ID number (CID) for use throughout the study. Participants will receive an automated email with their unique login details.

Participants will be directed to read the Participant Information Sheet and provide consent. The investigators will provide information on study protocols and participation details without disclosing the intervention arms explicitly, to maintain the integrity of participant responses and hence to ensure validity of results. It will be deleterious to the study to reveal the labels or the differences between study arms before participants complete both shops as this will likely confound participant responses. The consent form will state that in each of the shops there is a 50% chance that the participant will have to make actual purchases i.e. buy the groceries in the cart they checked out. In reality, it will be randomly decided earlier whether shopping trip 1 or 2 is the real shop. This will be achieved via a collaboration with a local online grocery provider, FairPrice.