Longitudinal Analysis of Mobile Money Nudge Efficacy on Smallholder Rice Farmers' Input Savings in the Kilombero Valley

{ "background": "Smallholder farmers in sub-Saharan Africa often struggle to save for essential agricultural inputs, constraining productivity. Mobile money platforms offer a potential channel for delivering behavioural interventions to encourage savings, but longitudinal evidence on their sustained efficacy is limited.", "purpose and objectives": "This study investigates the longitudinal effect of text-based behavioural nudges, embedded in mobile money transaction receipts, on the input savings behaviour of smallholder rice farmers. It aims to determine the intervention's impact over time and identify factors influencing its effectiveness.", "methodology": "A longitudinal, randomised controlled trial was conducted with a panel of farmers. Treatment groups received varied nudge framings (e.g., goal-setting, social comparison) on their mobile money receipts. Savings balances were tracked digitally. The primary analysis used a linear mixed-effects model: Yit = \β0 + \β1 Ti + \β2 Xit + \ + \εit, where Yit is the savings balance for farmer i at time t, $Ti$ is the treatment assignment, and Xᵢₜ are time-varying covariates. Inference is based on cluster-robust standard errors.", "findings": "The goal-setting nudge generated a significant and persistent increase in average savings balances for inputs compared to the control group. Farmers receiving this nudge were 1.7 times more likely (95% CI: 1.3 to 2.2) to reach their pre-stated savings target. The efficacy of social comparison nudges diminished after the initial intervention period.", "conclusion": "Behaviourally-informed mobile money nudges, particularly those focused on goal-setting, can durably improve smallholder savings rates for agricultural inputs. The effect is not uniform across nudge types, highlighting the importance of longitudinal evaluation.", "recommendations": "Agricultural digital finance products should incorporate simple, goal-focused messaging into their user interfaces. Policymakers and development partners should support the design