Unraveling Soft-Commitment: Evidence from a Field Experiment on Recycling

We run a randomized field experiment to evaluate the effectiveness of signing a soft-commitment in promoting recycling. The intervention is conducted in a Spanish densely populated city where a system of electronic bins was introduced for sorting bio-waste. To introduce the new sorting system, a team of environmental educators informed about it and invites citizens to participate in our study. The information received by the households included how to use the bin, where to find a container, what types of waste are disposed and what types are not disposed in that particular bin etc. The educators also suggested the minimum expected weekly use of the bin for that household (given household characteristics).

All participants signed an informed consent agreeing to participate in the experiment and allowing us to track the data coming from their household (control group). Additionally, half of the participants were randomly offered to sign a soft-commitment (treatment group) stating that they will sort bio-waste.

We will evaluate the treatment effect by exploiting real-time data on the use of bio-waste bins.

2019-01-28

2019-11-18

- %Weeks: proportion of weeks the container is used at least once
- # Uses: weekly average number of uses of the container
- Degree of fulfillment computed as #Use/MENUCO.

In 2018, the public company managing urban waste in Palma started a pilot program for recycling biowaste. Initially, the program was only introduced in some specific areas of the city. To avoid improper sorting, which would compromise the future use of bio-waste, bins were locked and can only be opened by scanning a personal card. The city transportation card (citizenship card) was used for that purpose. Bio-waste bins could only be opened with the card and the number of the card opening it was recorded by the electronic system of the bin. This provides digitalized and individualized data on organic recycling. We will exploit this real-time data to evaluate our intervention.

All participants signed an informed consent agreeing to participate in the experiment and allowing us to track the data coming from their household (control group). Additionally, half of the participants were randomly offered to sign a soft-commitment (treatment group). This commitment implied acquiring the compromise to recycle biowaste.

The fieldwork was carried by a team of environmental educators. It was implemented as an additional task during the informational campaign for introducing bio-waste sorting. They worked at different points of the pilot area. The timing of the intervention is the following:
1. Citizens approach the information desk.
2. Environmental educators inform about the introduction of bio-waste separation and solve citizens’ questions about it.
3. Citizens receive a kit for recycling including a bin for collecting bio-waste disposal and compostable bags.
4. Citizens were offered to participate in a study and to sign an informed consent if accepting. They were specifically informed that their household information on bio-waste disposals would be used for the study.
5. Participants answer a small questionnaire and were assigned to one of the experimental groups. In both groups, the educators announced the minimum number of bio-waste weekly disposals that the household is expected to do if they correctly sort bio-waste.
6. Participants in the treated group were offered to sign the soft-commitment.

We will combine the data coming from the field with the following:
1. Card information: user (anonymized) identifier, bin identifier, date, time when the card was scanned, time when the bin gate was open and time when the bin gate was closed.
2. Administrative data from the cards (ID and postal address). This allows us to match people living in the same households as one recycling unit.


Recruitment period: Recruitment of participating households took place between January 2019 until November 2019

Intervention evaluation period: The direct effect of the intervention will be evaluated using the real-time data from bio-waste bins from the moment of being recruited to the end of December 2019. We can also use data from January 2020 onwards to analyze a longer time horizon.
Data prior to recruitment time will be used for pre-treatment balancing tests.


Place of the intervention: Palma (Balearic Islands, Spain) The intervention is conducted only in the areas of the city where the bins for biowaste recycling were introduced. However, the bio-waste recycling program was not simultaneously introduced in all these areas. Implementation was done in different phases. The neighborhoods included in each phase for this intervention are:
Area 1 (since November 2018): Son Flor, Los Almendros-Son Pacs, Son Rapinya, Son Cotoner, El Fortí & El Camp d'en Serralta
Area 2 (since March 2019): Son Dameto Son & Espanyolet

Experimental condition assignment was done in alternation upon order of arrival at the information desk. That is, if the first citzen recruited on a given day was assigned to the treatment group, the one that immediately followed was assigned to the control group. to avoid spillovers, if a group of citizens was jointly informed, then the whole group was assigned to the same experimental group (the one that corresponds according to order of arrival) and group assignment continues in alternation afterwards.

Household level

No

1500 households (aprox.)

1500 households (aprox.) Given the real-time nature of bin usage data, we get an observation every time that a participating household uses the biowaste bin. We generally collapse this information at week level.

50% control and 50% treatment