Using the default rule to increase the demand of doggy bags in restaurants
This nudge was created by Massimo Cesareo with the help of Andrea Compiani, Magdalena Edyta Lopes, Paolina Stoyanova, Marianna Vaccaro, Francesco Pozzi & Paolo Moderato. The intervention took place at the restaurant RISE Live Bistrot near Milan.
To tackle food waste in the restaurants, NudgeItalia carried out an intervention to increase the demand for doggy bags in a pizzeria near Milano (Italy). While clients usually have to actively ask the waiters to pack their leftovers in a doggy bag, in the experiment the default rule was changed to automatically provide with a doggy bag when the clients had uneaten food on their plates, unless they actively choose to opt-out.
The participants of the study where the self-selected clientele of the pizzeria. Data were collected over the course of one month by counting the number clients who had leftovers (at least one slice of pizza left), and the number of demanded doggy bags.
During the first two weeks, the demand for doggy bags was simply measured. During the second two weeks, the intervention took place. In front of each client, we placed a double-sided poker-chip, with the two sides coloured in a different way, respectively green and red. The poker-chip was placed with the green side up by default. This signaled that the customer wanted a doggy bag if they had any leftovers. This means that the customers, in order to receive the doggy bag, just had to leave it on that side, while they had to turn it up on the red side to opt-out .
To make the intervention easily understandable for the customers, a centerpiece with simple instructions was placed on each table. In addition, a printed paper with the instructions was placed inside each menu. (See picture below)
A chi-square test was run to compare the data in the two conditions, showing a statistically significant difference between the first and the second phase. The percentage of demanded doggy bags increased by 44% during the second two weeks (85%) compared with the first two (41%).
The results confirmed our initial hypothesis. Manipulating the default rule showed to be an effective means to increase the demand for doggy bags in a pizzeria setting.
There has been given access to a blog post about this nudge (in Italian). Here you can find more relevant information on the nudge.
Sunstein, Cass R. “Choosing not to choose.” (2015). ; Johnson, Eric J., and Daniel Goldstein. “Do defaults save lives?.” Science 302.5649 (2003): 1338-1339.