AEA RC T Registr y

The American Economic Association's registry for randomized controlled trials

We designed a randomized field experiment to evaluate the effectiveness of monetary incentives to promote recycling. The intervention is conducted in a Spanish densely populated city where a system of electronic bins was introduced for separating bio-waste. A team of environmental educators provides information on this bio-waste recycling program and invites citizens to participate in our study. Households that accept to participate in the study are randomly assigned to an incentivized and to a non-incentivized group.

In the control group, the probability of winning a monetary prize will be independent of the number of uses of the bio-waste bin. In the treatment group, the probability of winning the prize will depend on the number of weeks that the household has made at least one use of the bin per week. In this way, one group receives economic incentives to recycle while the other does not.

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

2020-11-02

2022-01-31

Weekly number of bio-waste bin usages
Making at least one usage per week (binary variable)

Complying with at least 2 usages per week (binary variable)

We designed a randomized field experiment to evaluate the effectiveness of monetary incentives to promote recycling. We are exploiting real-time microdata on bio-waste disposal to evaluate the intervention. The field-work is executed by a team of environmental educators who are interacting directly with citizens in a Spanish densely populated city. The educators will be present at different informational points in the area of the study. The educators provide information on the recycling program, provide households with a free recycling kit, and invite citizens to participate in the study. On specific days with a high expected influx of people, members of the research team might assist environmental educators to administer the treatment.

Participating households will be randomly assigned to a control group (no monetary incentives) and a treatment group (monetary incentives). Households are assigned to one of these two groups by order of recruitment in a staggered way. That is, if the first household is assigned to the treatment group, then the second one is assigned to the control group, and so on.

The intervention is conducted only in the areas of the city where the electronic bins for biowaste recycling are introduced. However, the installation of the biowaste containers is not simultaneous in all these areas. As a consequence, we run the recruitment of participating households in two different periods. The first one corresponds to the period November 2020-March 2021 and the second one corresponds to the period April 2021-November 2021. Only one recruitment period was initially planned, however, the recruitment of participating households was slower than initially expected which induced the research team to open the second period. This second recruitment period is carried out before conducting any type of data analysis.

The two treatments of the intervention are characterized as follows:

(a) Control group (no incentives): By participating in the study, they can win a prize in cash. A total of 10 prizes of € 280 each will be raffled among those who have agreed to participate in the study (5 prizes corresponding to the first recruitment period and 5 prizes corresponding to the second one). The prize draw is completely independent of the use of the bio-waste container.
First recruitment period: The draw will take place in May 2021.
Second recruitment period: The draw will take place in January 2022

(b) Treatment group (incentives): By participating in the study, they can win a prize in cash. A total of 10 prizes of € 280 will be raffled among the participants (5 prizes corresponding to the first recruitment period and 5 prizes corresponding to the second one).

- The prizes for the first recruitment period will be drawn based on the information registered in the system of electronic bins from the moment of the intervention until 15/04/2021. Each week that any card from the household is registered in the bio-waste container system, the household will acquire a ticket for the raffle. The more tickets the household obtains, the higher chance of winning one of the prizes. The draw will take place in May 2021.

- The prizes for the second recruitment period will be drawn based on the information registered in the system of electronic bins from the moment of the intervention until 15/12/2021. Each week that any card from the household is registered in the bio-waste container system, the household will acquire a ticket for the raffle. The more tickets the household obtains, the higher chance of winning one of the prizes. The draw will take place in January 2022.

A reminder will be sent to the two experimental groups at the time when the removal of the incentives approaches (between 1 and 7 days in advance).

Not available

Households are recruited when one of its members meets an environmental educator and accepts to participate in the study. Households are assigned in a staggered way to one of the two experimental conditions according to the order of recruitment. That is, if the first household recruited on a given day is assigned to the treatment group, then the subsequent household is assigned to the control group. Households are subsequently assigned to each group according to this logic. This maximizes the balancing between the two groups within the recruitment day.

Household level

No

Expected: 500 to 2500 households

Expected: 500-2500 households. Given the real time nature of the data collection, we get an observation each time a household member uses the container.

50% control 50% treatment