Effect of persuasive messages on National Health Service Organ Donor Registrations: a pragmatic quasi-randomised controlled trial with one million UK road taxpayers
ConclusionsShort persuasive messages alongside a prompt can persuade more ODR sign-ups for individuals renewing their road tax than a prompt alone. The most effective message remains in place today. Since the trial in 2013, the same message has been implemented across 25 government end-of-transaction websites on GOV.UK, resulting in 529,000 new registrations to the ODR  up to 31st October 2017. (Source: Trials)
Source: Trials - September 21, 2018 Category: Research Source Type: clinical trials

Do Taxes Reduce the Purchasing of Soda?
Conditions:   Obesity;   Diabetes Intervention:   Behavioral: Simulated tax via 3 cent per ounce price increase Sponsor:   Grant Donnelly Not yet recruiting - verified September 2016 (Source: ClinicalTrials.gov)
Source: ClinicalTrials.gov - September 3, 2016 Category: Research Source Type: clinical trials