This study investigates a simple, generic and easily scalable nudge to promote healthy and sustainable food choices at conferences by using a vegetarian lunch-default as a normative signal.

Methods At three conferences, participants registering electronically were randomized into two groups: Group 1 received a standard lunch registration presenting a non-vegetarian buffet as the default, but allowing the active choice of a vegetarian option; Group 2 received a registration presenting a vegetarian buffet as the default, allowing the active choice of a non-vegetarian option. The study also assessed gender differences for two of the conferences and the participants' acceptance of the nudge at one of the conferences.

Results In experiment A the vegetarian choice increased from 2% to 87% (N = 108, P

Conclusions Changing the lunch-default to a vegetarian option is an effective, generic, easy to scale and well-accepted nudge to promote healthy and sustainable food choices at conferences.

Question 1.2: Compare any two experiments of the paper: who are the treated units, what is the response variable and what is the treatment? Discuss the role of randomization and the di erences in the treatment choices. Why did the authors rely on multiple experiments?

Question 1.3: Discuss considerations of internal and external validity throughout the whole study (all three experiments), highlighting potential trade-o s in general and how they relate to the studies carried out.

Question 1.4: The paper presents group diferences in a plot and discusses these in text. Pick one compar- ison and carry out step-by-step the hypothesis testing (with the ? value of your choice) for a diference in proportion.

Question 1.5: The paper discusses some diferences between men and women. Present a brief outline of a study that you would design to get a more detailed view of these dierences and the potential reasons behind them.

Please help me, also through article: https://academic.oup.com/jpubhealth/advance-article/doi/10.1093/pubmed/fdz154/5637580

Lunch choice (standard vs. vegetarian) at three conferences 120% percentgae of particapnts in group 98% 100% 94% 94% 87% 86% 87.59 896 87% 80% 60% 40% 20% 1396 12 59% 1196 13% 6% Group 2 Group 2 Group 1 Group 2 Group 2 Group 1 Group 1 Group 1 Experiment 1 (N=108) Experiment 2 (N=112) Experiment 3 (N=110) Total effect (N=330) "Non-vegetarian Vegetarian