Intervention (Hidden)
I conduct a field experiment (RCT) in which an information-based recycling intervention was delivered to randomly selected households in the city of Quelimane, Mozambique. The project was implemented in partnership with the municipal government under the name “ReCiclar com Quelimane'' (ReCycling with Quelimane). The intervention ran from July to November 2025 and consisted of a household-level information campaign on recycling, delivered through door-to-door visits, combined with free collection of recyclable waste.
Recyclable waste collection was carried out by bicycle taxi drivers (“cyclists”), who constitute the city’s main transport network. Cyclists were engaged as waste collectors in a manner that complemented their regular work as bicycle taxis. During the intervention period, cyclists received the same information as households, via targeted videos shown during structured visits. I now describe the design of the information campaign.
The information campaign:
The information campaign consisted of three scripted visits to sampled households and cyclists. The first visit took place in July 2025, the second in August 2025, and the third in November 2025. The November visit took place after the midline survey and was used as a final booster session to reinforce the earlier messages. At each visit, participants watched a short video combining basic information on recycling with targeted behavioural encouragement. Videos for households and cyclists differed in focus: household videos emphasised waste separation, whereas cyclist videos emphasised waste collection and programme reinforcement among their client base.
All videos introduced the concept of recycling and its benefits, but each of the three rounds focused on a distinct thematic component. The first video defined recycling, highlighted its environmental benefits, and placed particular emphasis on neighbourhood cleanliness and improvements to community wellbeing. It then focused on plastic waste, explaining why plastics impose environmental harm and concluding with a list of plastic items accepted for recycling.
The second video revisited the general problem of waste accumulation before turning to metal and glass. It explained the hazards associated with these materials and provided examples of recyclable items in each category. The third video summarised the content of the first two sessions, reiterated the full list of recyclable plastic, metal, and glass items, and stressed the importance of broader community engagement to reduce visible waste accumulation in neighbourhoods.
The household video in the third round encouraged participants to share both the information received and the contact details of their “everyday cyclist’’ (the specific cyclist assigned to their household) with close neighbours. Cyclists, by contrast, were encouraged to reinforce the informational messages with all passengers they transported and to collect separated waste bags when contacted.
In all household videos, participants were encouraged to reuse existing rice or flour sacks available at home for storing separated recyclables and to contact their everyday cyclist once the bag was full. Cyclist videos, in turn, instructed them to deliver collected recyclables to a storage point established by the municipality in the city centre. At this point, recyclables were weighed by material type (plastic, glass, metal), and cyclists received a pre-specified payment per kilogram, with posted prices visible at the centre. All videos incorporated visual illustrations to facilitate comprehension.
The nudge treatment
To investigate the role of social visibility in household engagement with waste separation, I included an additional treatment arm featuring a conspicuous signalling device in the form of a thermometer poster. During the baseline survey, households assigned to this group received a postcard displaying a thermometer with five uncoloured bars. The videos explained that each time recyclables were collected from that household, the cyclist should colour in one of the bars. Field administrators were instructed to write down the household's ID at the top corner to facilitate tracking.
The videos also informed households that the most engaged participants, measured by the number of fully coloured thermometers and the kilograms of recyclables delivered to the storage centre, would have their names and photographs displayed on a public poster located in the city centre. To maintain engagement, the midline visit included a small reward. Households that had completed at least one thermometer received a sticker with the project logo and a new thermometer card.
Field administrators were instructed to take a photograph of the thermometer display and to record the number of coloured bars in every visit and in every survey wave. These photographs and counts provide administrative measures of adherence to the nudge treatment and of household engagement throughout the intervention.