Randomization and blinding
non-alcoholic, non-alcoholic beverages
A random number table was used to perform simple randomization and to select the number of participants in the intervention group. After the eligibility and exclusion criteria were confirmed and consent was obtained, participants were allocated into either the intervention or control group and notified of the randomization results via e-mail within 2 weeks after the briefing. Allocation was performed by Investigator K, without disclosing the allocation or its order to the other investigators. Because people can choose their preferred non-alcoholic beverages in their everyday lives, and since the dropout rate might be increased if participants were provided with beverages that they did not like, those in the intervention group were not blinded so that they could choose their non-alcoholic beverages. For this reason, no items to facilitate blinding were provided to the control group participants during the study, but instead non-alcoholic beverages were provided after the study period had ended. The drinking diary data were evaluated by Investigators K, S, and O, who were blinded to the allocations of participants in both groups. Investigator D was not involved in briefings, randomization, questionnaire development, or the evaluation of drinking diary data, and therefore was able to perform data analysis in a blinded manner.