Evaluating A Promising Food Policy Intervention Using NUSMart: A Sin-Tax Scheme

Using a 3-arm randomized controlled trial, the investigators aim to rigorously evaluate the effects of two different taxation policies on diet quality. The first is an implicit sales tax that will be levied only on beverages in a manner that mirrors the current Kingdom of Saudi Arabia (KSA) beverage taxes and the second is an explicit Nutri-Score (NS) based tiered tax that is levied on all food and beverage products. The investigators will use an experimental online grocery store, called NUSMart, which is similar in design to commercial web-based grocery stores to test these two taxation policies. Participants will be randomly assigned to one of the following arms and asked to complete a one-time hypothetical shop.

Arm 1 (Control): Participants will experience a default version of NUSMart which replicates the traditional shopping experience of online grocery stores with no FOP labels.

Arm 2 (Implicit Tax): Same as Arm 1 NUSMart except that an implicit tax will be levied only on beverages: a 50% sales tax on carbonated drinks and sugar-sweetened beverages (SSBs) and 100% tax on energy drinks (milk, milk-based products, and natural fruit juice are excluded).

Arm 3 (Explicit Tiered Tax): Same as Arm 1 NUSMart except that an explicit tiered tax based on (underlying) NS is levied on (sale price of) all food and beverages. NS assesses overall nutritional quality of products on the basis of 7 nutrients (calories, saturated fats, sugar, salt, fiber, protein and percentage of fruits, vegetables and nuts) from A to E (best to worst). In this arm, the investigators implement a 20% sales tax on the retail price for NS D beverages and 10% for NS D foods along with a 50% sales tax on NS E beverages and 20% on NS E foods.

The investigators hypothesize the following:

Hypothesis 1: Diet quality of food purchases, measured by the weighted average Nutri-Score point, will be highest in the explicit tiered tax arm, followed by the implicit tax arm, followed by the control.

Hypothesis 2: Average calories, sugar, sodium, and saturated fat per serving will be lowest in the explicit tiered tax arm, followed by the implicit tax arm, followed by the control.