Effect of a sugar-sweetened beverage price increase on healthiness of purchases and business outcomes in an Australian university

In December 2016, Monash began a transition to healthier food retail vending across their campuses. Monash University adopted the voluntary Victorian Government Healthy Choices guidelines for vending machines in April 2017. These guidelines specify that unhealthy ‘red’ foods and drinks should comprise less than 20% of available items, and healthy ‘green’ food and drink should comprise at least 50% of available items. The focus of the current intervention is on 60 Western-style vending machines which sell both drinks and snacks across the campuses. The RCT will run on all Victorian Monash campuses for 24 months from March 2020 (beginning of semester 1) to February 2022 (prior to Semester 1 2022). A 2 x 2 factorial design will be used to test the independent and combined effect of two interventions: a 20% price increase on ‘red’ drinks, and the addition of pricing labels at the point-of-selection. The four conditions defined by these two interventions are: 1. 20% price increase on ‘red’ drinks 2. Prominent price labels added to all drinks 3. 20% price increase on ‘red’ drinks + Prominent price labels added to all drinks 4. Control- no prominent price labels or pricing changes Rectangular price labels will be inserted directly below each item. They will measure approx 2cm high by 7cm wide. They contain the item number (for selection at the payment terminal), the price (text approx 1cm high and 3cm wide) and a round coloured sticker indicating the traffic light classification with a corresponding message (red= "limit"; amber="choose carefully"; or green= "best choice"). Note that all machines at baseline included item labels with the item number and traffic light labels, but no price. Photographic audits of machines will be conducted by study personnel at at 6 month intervals: month 1 (March 2020), 6 months (planned for September 2020, delayed to December 2020 due to COVID-19 campus closures), 12 months (March 2021), 18 months (September 2021), 24 months (February 2022). This will be used to determine implementation and maintenance of the intervention (i.e. correct display of prices and prominent price labels according to machine allocation), as well as collect covariates for analysis such as machine proximity to Asian-style vending machines.