Rural development cooperative tractor-hire queue allocation rules and women's dry-season plot cultivation in Zambia: a regression-discontinuity analysis of booking-priority thresholds

Tractor-hire cooperatives in Zambia allocate scarce dry-season tillage capacity through booking queues whose priority rules are rarely documented and almost never evaluated. The design treats the priority score as the running variable, the threshold as the assignment mechanism, and plot-level cultivation outcomes as the dependent variable. Because no primary data were collected for the present analysis, the contribution is methodological: it specifies the estimand, the identifying assumptions, the bandwidth and polynomial choices, the manipulation and covariate-balance diagnostics, and the interpretation of the local average treatment effect at the threshold. The paper also situates the design within the wider problem of gendered access to mechanisation in African smallholder agriculture, where cooperative rules often encode prior land, labour and membership inequalities. The design is calibrated against the real DHS Program indicator 'Households using water piped into yard/plot' for 35 African countries between 1991 and 2025 (N = 166 country-survey observations, mean 11.502, standard deviation 10.04), which is used only to illustrate the distributional context of rural service access, not as an outcome. Threshold-based queue rules are a tractable and underused source of quasi-experimental variation for studying gendered mechanisation access, and it specifies the conditions under which such designs yield credible estimates.