Smallholder farming systems in South Africa face challenges related to yield improvement due to various factors such as climate variability and limited access to modern agricultural technologies. A systematic literature review will be conducted to identify and analyse studies employing difference-in-differences (DiD) models to measure yield changes in smallholder farming systems across different regions of South Africa. The review will include methodological evaluations, data sources, model specifications, and results interpretation. The analysis revealed that the DiD model was predominantly used for comparing pre- and post-intervention yields, with some studies incorporating control groups to mitigate potential confounding variables. However, there is variability in how these models are applied across different regions, affecting their generalizability. While the DiD model has shown promise in measuring yield improvements among smallholder farmers, its effectiveness varies depending on region-specific contexts and data quality. Future research should consider expanding the DiD model to include more complex interventions and incorporate longitudinal data for enhanced robustness. Additionally, greater attention should be paid to methodological consistency across studies. Model estimation used =argmin_ᵢ (yᵢ, f_ (xᵢ) ) +₂², with performance evaluated using out-of-sample error.
Nkosi Mabaso (2003) studied this question.