Browsing by Author "Dallu, Abdallah Mambo."

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    Bank size as a mediating mechanism between financial soundness and operational efficiency: evidence from Islamic banks in sub-Saharan Africa
    (Emerald Publishing., 2026) Njogo, Michael Njoroge.; Dallu, Abdallah Mambo.; Korir, Fiona Jepkosgei.
    Purpose This study examines whether bank size mediates the relationship between financial soundness and operational efficiency of Islamic banks in sub-Saharan Africa (SSA), where the sector remains small despite growing policy relevance. Design/methodology/approach Panel data from 35 Islamic banks (2010–2024) were analysed using bias-corrected Variable Returns to Scale scores from the Simar–Wilson two-stage Data Envelopment Analysis. A panel-based mediation model with two-way fixed effects was employed, with bank size (log of deposits) as the mediator. Findings Financial soundness significantly improves operational efficiency, with asset quality exerting a negative effect and earnings stability a positive effect. However, financial soundness does not significantly influence bank size, and bank size does not significantly affect efficiency once soundness is controlled for. Consequently, the mediation hypothesis is not supported, indicating that scale does not function as a transmission mechanism in SSA Islamic banking. Research limitations/implications The findings caution against consolidation-led efficiency strategies and support policy emphasis on governance, regulatory infrastructure and operational capacity building to enhance inclusive and sustainable Islamic banking development. Originality/value This study provides one of the first empirical assessments from SSA that explicitly tests the mediating role of bank size in the soundness–efficiency relationship. The findings show that scale expansion does not operate as a transmission mechanism, suggesting that scale-driven efficiency strategies may have limited applicability.
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    Financial soundness and operational efficiency of Islamic banks in Sub-Saharan Africa: evidence from a bias-corrected DEA and panel regression framework
    (Emerald Publishing., 2026) Njogo, Michael Njoroge.; Dallu, Abdallah Mambo.; Korir, Fiona Jepkosgei.
    Purpose This study examined the effect of financial soundness on the operational efficiency of Islamic banks operating in Sub-Saharan Africa (SSA), a region characterized by emerging Islamic banking systems and constraints. It focused on how capital adequacy, asset quality, earnings quality and liquidity management influence efficiency outcomes. Design/methodology/approach The study applies a Simar–Wilson two-stage data envelopment analysis framework to a balanced panel of 35 fully-fledged Islamic banks in SSA from 2010 to 2024. Bias-corrected efficiency scores are estimated under variable returns to scale and subsequently analyzed using a panel regression framework with two-way fixed effects and robust standard errors to control for unobserved heterogeneity across banks and time. Findings The findings revealed a heterogeneous relationship between financial soundness and operational efficiency: asset quality was positively and significantly associated with efficiency, whereas earnings quality exhibited a negative relationship, indicating a profitability–efficiency trade-off. Capital adequacy showed no direct effect, while liquidity management demonstrated a weak and context-dependent influence. Practical implications The analysis is limited to fully-fledged Islamic banks with complete data. The findings suggest that regulators and managers should prioritize asset quality improvement and efficiency-oriented strategies over balance-sheet expansion. Originality/value The study provides one of the first ever comprehensive, bias-corrected DEA empirical assessments of operational efficiency in Sub-Saharan Africa in Islamic banking. By distinguishing operational efficiency from traditional profitability measures, it challenges the assumption that improved financial soundness inherently enhances efficiency in emerging Islamic banking markets.