Subsistence farmers may find themselves unable to share in the market-based growth for lack of skill and labour, which would suggest that aid interventions upgrading skills through better extension services, could greatly improve market participation and commercialisation by smallholders. Ngo (2006) confirms the importance of literacy and numeracy skills as pre-conditions for agricultural growth. Calculating the effect of educational attainment on rice productivity in Vietnam, the author finds that the returns to literacy and to holding upper secondary diplomas on rice yields are 38% and 31% respectively.