Using systems thinking to generate novel research questions for the evaluation of sugar-sweetened beverage taxation policies

Sugar-sweetened beverage (SSB) taxes have been recommended by the WHO, introduced in over 85 countries, and assessed through an increasing number of evaluations.

However, few studies have applied systems thinking to generate questions exploring the range of ways in which an SSB tax, and the system within which it is embedded, have adapted to one another over time.

We demonstrate how adopting this perspective could advance the field. A systems thinking perspective focuses on how the intervention and system adapt to one another. Interventions are viewed as disruptions to a complex system in which the system may change how the intervention operates over time, and the system may coevolve to minimise or amplify disturbances caused by the intervention.

As the literature on SSB taxes matures, there is a scope to employ a systems perspective to develop novel research questions, based on a deeper understanding of the system’s boundaries, its observed patterns over time, and its underpinning assumptions and structure.

Addressing systems-informed questions could address gaps in the SSB literature, including: (1) considering intervention and system coevolution over time, (2) identifying further unanticipated consequences and (3) building deeper understanding by drawing on diverse types of studies.

A systems perspective offers insights that can help to strengthen health-promoting impacts, minimise health-harming impacts, and support policy sustainability and adaptation over time.

We have focused on SSB taxation, but other types of health policy evaluations, including other health taxes, would also benefit from the increased use of systems thinking-informed research questions.