Beverage Choice Decisions (BCD) study

The BCD study uses a discrete choice experiment approach to explore the effect of changing beverage prices and exposure to educational messaging on participants' selection of sugary and non-sugary beverages. It does not use a traditional allocation of treatment and control groups but rather the experiment allows subsequent modelling of predicted effect at a population level of changes in beverage prices and volumes. Study participants will complete an online experiment in which they will be given a series of 20 hypothetical non-alcoholic beverage purchasing tasks in a convenience store setting. In each task, participants will choose between seven sugary and non-sugary beverage alternatives (energy drink, plain low-fat milk, flavoured milk, bottled water, regular soft drink, diet soft drink, fruit juice, no beverage) and a no beverage alternative that will be described by attributes of those alternatives (price and volume). Prices and volumes which varied between scenarios with four generic volume levels (200mL, 330mL, 460mL, 600mL) and four alternative-specific price levels as follows: Energy drink: $2.00, $3.30, $4.60, $5.90 Plain low-fat milk: $1.00, $2.30, $3.70, $5.00 Flavoured milk: $2.00, $3.50, $5.00, $6.50 Bottled water: $1.00, $2.30, $3.70, $5.00 Regular soft drink: $2.00, $3.50, $5.00, $6.50 Diet soft drink: $2.00, $3.50, $5.00, $6.50 Fruit juice: $2.00, $3.30, $4.60, $5.90 As this is not a traditional trial, a total of 160 choice scenarios were generated using NGene software to minimize the correlation between displayed prices and volumes (in order to isolate the effect of changing each). Each participant was randomly allocated to complete one of eight blocks of 20 choice scenarios. The responses from participants will be incorporated into a discrete choice model, which will then allow generation of the predicted impact of hypothetical beverage price changes on population purchases of sugary and non-sugary beverages. Approximately half of participants will also be shown an educational message discouraging sugary drink consumption, prior to completing the choice scenarios, from the rethinksugary drink campaign (Copyright held by Cancer Council Victoria). The graphic message describes the sugar content of a selection of common SSBs accompanied by the message "you wouldn't eat 16 teaspoons of sugar". The message will be displayed on the screen within the online experiment for 5 seconds.