Décomposition structurelle des multiplicateurs sectoriels, fuites et rétroactions dans une économie duale : une analyse en matrice de comptabilité sociale pour le Cameroun[Sectoral multipliers, leakages and feedbacks in a dual economy: Evidence from a social accounting matrix for Cameroon]

This article identifies the channels through which a sectoral demand shock propagates across Cameroon's dual economy. Using the 2019 social accounting matrix (SAM), comprising 190 accounts, 46 economic sectors and 14 household categories defined according to employment status and place of residence, the analysis combines the decompositions proposed by Pyatt and Round (1979) and Stone (1985), a comprehensive decomposition of leakages, structural path analysis and shock simulations based on four closure scenarios. Trade margins, previously treated as leakages, are endogenised. The results show that the closed income-expenditure loop accounts for 61.3 per cent of the total multiplier. The household income multiplier is negatively correlated with the share of capital in value added (ρ = -0.87): it stands at 2.05 in agriculture, compared with 0.81 in oil extraction, where 42.6 per cent of the injection leaks out in the form of savings, mainly by companies. Fiscal feedback exacerbates the loss of household income following an oil shock by 28 per cent, compared with 6 per cent for an agricultural shock. Furthermore, poor households capture 43.6 per cent of the gains generated by an agricultural shock, compared with 23.7 per cent in the case of an oil shock. These results argue in favour of agro-industrial diversification supported by a counter-cyclical fiscal rule.