<![CDATA[Upland rice farming sustains rural livelihoods in geographically constrained areas but remains lowproductivity. This study examines the determinants of upland rice productivity in the Caraga Region, Philippines, using cross-sectional data from 239 farmers and estimating a log-linear Cobb-Douglas production function by ordinary least squares. The results show that seed use (β = 0.338), pesticide application (β = 0.214), man labor (β = 0.237), and seedling rate (β = 1.229) significantly and positively influence output, with seedling rate exhibiting the largest elasticity. Farmer age (β = 0.587), years of schooling (β = 0.173), and family labor (β = 0.240) also have positive and significant effects, whereas household size (β = −0.585) has a negative effect on productivity. Fertilizer use (β = 0.005), man-animal labor, and institutional variables such as extension contact were not statistically significant. The model explains a substantial proportion of the variation in output (R² = 0.828; Adjusted R² = 0.686). The estimated sum of elasticities, 2.165, indicates increasing returns to scale, implying that a 1% increase in all inputs leads to a 2.17% increase in output. Diagnostic tests confirmed no severe multicollinearity and no significant heteroskedasticity. While the findings highlight the importance of coordinated input use and human capital in improving productivity, the analysis relies on cross-sectional survey data and assumes input exogeneity, which may not fully capture technical inefficiency or unobserved biophysical factors. These results provide an empirical basis for understanding input responsiveness in environmentally sensitive upland rice systems.]]>
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