Phone-call reminders narrow the intention-action gap by increasing follow-through for a residential tree giveaway program

Residents' participation is key to the success of urban tree planting programs, yet a gap between resident intentions and participation actions may limit the benefits provided by such programs. Philadelphia Parks and Recreation (Pennsylvania, US) has conducted tree giveaway events for residents since 2012 with the goal of increasing tree canopy. But some residents who register for giveaway events do not follow through and attend the event, creating logistical and planning difficulties that increase program costs. We tested whether phone call reminders could narrow the intention-action gap and increase the likelihood that registered residents attend a yard tree giveaway event. A total of 251 people registered for a spring 2018 giveaway event. Registered participants were randomly assigned to receive either a standard set of email and paper reminders representing normal program operations (126 participants), or to receive up to two phone call reminder attempts in addition to the standard reminders (125 participants). The follow-through (attendance) rate among registered participants who received phone calls was compared to those who did not receive phone calls. The phone calls increased attendance by 16 percentage points, a statistically significant increase. Based on this effect size and time spent making phone calls, staff spent an average of 12.4 min making phone calls per additional attendee. This study demonstrates the feasibility of using an experimental approach to facilitate evidence-based decisions in an urban tree planting context. Further research is needed to evaluate the impacts of communication strategies on resident behavior in tree planting and distribution programs.