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Beyond Discrete Choice in Health: Multiple Discrete-Continuous Extreme Value (MDCEV) Models
July 12, 2022 @ 9:00 am - 10:00 am EDT
Presenter: John Buckell, University of Oxford
To compare the impacts of providing brief advice (A), brief advice plus individually-tailored shopping advice (A+S) or taxation (T) and combinations thereof, on the amount of saturated fat (SFA) in consumers shopping baskets relative to control.
Econometric analysis and simulation using data from a randomized controlled trial. 113 adults (>=18 years with LDL cholesterol >3mmol/L) in the Oxfordshire area in the UK were allocated to receive either A, A+S, or usual care (control). Shopping was recorded through loyalty cards before and for 3 months after intervention, allowing us to measure participants’ sensitivity to price. We also tested a hypothetical â€˜Danishâ€™ fat tax of Â£1.70/kg on all products with more than 2.3g of SFA/100g. Simulation exercises compared total SFA (g/week) in participants’ shopping baskets in individual interventions and plausible combinations. Data were analysed in a multiple discrete-continuous extreme value (MDCEV) model.
There was a significant reduction in SFA content of baskets relative to control for A -12.2g; 95% CI: -18.3g to â€“5.3g, T = -29.3g; 95% CI: -32.3g to -26.1g) and A+T (-42.0g; 95% CI: -48.7g to -35.5g), but these interventions were significantly less effective than A+S (-62.8g; 95% CI: -95.7g to -32.8g) and A+S+T (-84.5g; 95% CI: -114.4g to -56.8g). Spreads, deserts/sweet, and dairy products made the largest contributions to SFA reductions.
Individually-tailored shopping advice, alone or in combination with a tax, was most effective at reducing purchased saturated fat. Tax enhanced the effect of basic advice and tax alone outperformed basic advice in reducing SFA in shoppers’ baskets. Saturated fat intake in the UK (13.5% energy) is significantly higher than dietary recommendations (10% energy) and these data provide evidence to inform policymaking to support changes towards a healthier diet.