Providing Feedback on recycling performance: a field experiment

We designed a randomized field experiment to evaluate the effectiveness of providing information (feedback) about its own recycling performance 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 bio-waste recycling 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 of and what types are not disposed of in that particular bin etc. The educators also suggested the minimum expected weekly use of the bin for that household (given household characteristics)

Once the informative sessions provided by the team of educators finishes, we randomize the subjects using a computer, assigning them to a control group (no feedback) or to the treated group (feedback). The intervention consists of sending correspondence to those that agree to participate in the study. The difference between the treated and the control group consists of the information received.
- The group without feedback (control) receives general information about the program and a reminder about the information received from the environmental educators.
- The group with feedback (treated) receives general information about the program and a reminder about the information received from the environmental educators as well as information about its recycling performance. Moreover, the households in the treated group receive information if they did comply or not with the expected weekly use of the bin.

In this way, households in the treated group are the only ones that receive information about their own recycling performance whereas households in the control group only receive general information about the program.

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

2020-02-11

2020-02-15

- %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.

We designed a randomized field experiment to evaluate the effectiveness of providing information (feedback) to promote recycling. We are exploiting real-time microdata on bio-waste disposal to evaluate the intervention. The fieldwork is executed by a team of environmental educators who recruited citizens to participate in our study. The study was implemented in Palma (Balearic Islands, Spain). The educators were present at different informational points in the area of the study. The educators inform about the recycling program, provide households with a free recycling kit, and invite citizens to participate in the study.

We randomized the subjects with a computer, assigning them to a control group (no feedback) and to a treatment group (feedback). The intervention consists in sending correspondence to participants with different information:
- The control group receives general information about the program and a reminder about the information from the environmental educators.
- The treatment group receives general information about the program and a reminder about the information received from the environmental educators (as the control group). They also receive information about their environmental performance, measured according to the expected number of weekly uses of bio-waste bins.

Importantly, participating households have already participated in a previous intervention consisting in being offered to sign a soft-commitment on recycling (see trial AEARCTR-0007758). Thus, in the current intervention two mechanisms are combined: i) the soft-commitment and ii) providing feedback to the household about their recycling performance.
According to this double intervention, the provision of feedback was randomized within each pre-existing experimental condition (soft-commitment and no soft-commitment). Summing up, we aim to analyze the effect of providing feedback and its interaction with the preceding soft-commitment intervention. This results in a 2x2 design with the following 4 experimental groups:
Among those that in the first intervention were not treated (the no-commitment group):
(1) No commitment and No feedback: half of the households receive a leaflet with general information about the introduction of the installation of the biowaste bin and a reminder about the minimum expected number of uses of the biowaste container (MENUCO).*
(2) No commitment and Feedback: The remaining half of the households of the no-commitment group receive the same exact information (general information about the program and a reminder about the MENUCO) and additionally each household receive information about its recycling performance (to be described below)
Among those that in the first intervention were treated (the commitment group):
(3) Commitment and No feedback: half of the households receive a leaflet with general information about the introduction of the installation of the biowaste bin and a reminder about the minimum expected number of uses of the biowaste container (MENUCO) they committed to complying with.*
(4) Commitment and Feedback: The remaining half of the households of the commitment group receive the same exact information (general information about the program and a reminder about the MENUCO they committed to complying with) and additionally they receive information about its recycling performance (to be described below)

*Note that a small difference exists in the feedback received by groups 1 and 3: group 1 receives a reminder about its recommended MENUCO whereas group 3 receives a reminder about the MENUCO they committed to complying with. Similarly, the difference between groups 2 and 4 is the following: group 2 receives a reminder and feedback about its environmental performance with regard to its recommended MENUCO whereas group 4 receives a reminder and feedback about its environmental performance with regard to the MENUCO they committed to complying with. For more details, see trial AEARCTR-0007758.

The feedback about the recycling performance of the household was generated according to the proportion of weeks that the household made a use of the recycling bins according to its minimum expected number of uses (i.e. if during the evaluation period their number of uses is equal or greater than the MENUCO). The weeks included in the computation of this proportion from the moment of being recruited to the end of December 2019. This proportion was categorized in the following way for producing the feedback:
a) Satisfactory (green letters): whenever the household complies with the MENUCO at least 7 weeks out of 10.
b) Could be better (orange letter): whenever the household complies with the MENUCO between 5 and 7 weeks out of 10.
c) Unsatisfactory (light red): whenever the household complies with the MENUCO between 3 and 5 weeks out of 10.
d) Very unsatisfactory (dark red): whenever the household complies with the MENUCO less than 3 weeks out of 10.

The categorization includes a text in the corresponding color (satisfactory, Could be better, Unsatisfactory, and Very unsatisfactory) together with a colored smiley (see document attached) where the category assigned to the household was enlarged and highlighted whereas the other categories were lighter and smaller. Finally, a motivational sentence accompanied each of the categories. How the different categories were constructed was included in the letter as a footnote.


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

Intervention evaluation period:
The correspondence was sent on February 10th. The households received the letters between the 11th and 12th of February (we incorporate few letters with no information to our own addresses to check the arrival date)
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 July 2020. We will also use data from August 2020 onwards to analyze long-run effects.
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

Covid-19: Households receive letters between the 11th and 12th of February. This is approximately one month before the public health emergency caused by the COVID 19 forced the Spanish government to declare the state of alarm (a general and intense lockdown) on the 14th of March.

In the preceding soft-commitment intervention (trial AEARCTR-0007758) subjects were randomly assigned in alternation upon order of arrival at the information desk. That is, if the first citizen recruited on a given day was assigned to the soft-commitment group, the one that immediately followed was assigned to the control group.

For the present feedback intervention randomization was stratified within each experimental group in the preceding intervention, resulting in a 2x2 design. The randomization within each group was done by a computer with 50% in each group receiving no feedback and 50% receiving feedback.

Household level

No

1500 households (aprox.)

1500 households. 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% feedback and 50% no feedback