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Small Area Risk Mapping of Under-five Mortality: A District-level Analysis using Parametric Approach

Received: 30 November 2025     Accepted: 20 December 2025     Published: 20 January 2026
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Abstract

Mortality of under-five children remains a pressing public health concern in Tanzania, with spatial disparities contributed by the intersection of socioeconomic, health and environmental factors. This study employs Bayesian techniques and epidemiological spatial methods to estimate and map district-level under-five mortality, focusing on malaria prevalence, maternal education and source of drinking water. The districts with high risk are identified using georeferenced data of under-five mortality from recent Tanzania Demographic and Health Survey. We estimated the relative risk (RR) of under-five mortality within a hierarchical Bayesian spatial framework using three priors namely Besang-York-Mollie (BYM), Dean & Cressie (DC) and Leroux (BMY2). The model performance was evaluated using Watanabe-Akaike Information criterion (WAIC) to identify the best, from which the relative risk of under-five mortality was estimated and visualized using interactive and static maps. The Leroux (BYM2) model effectively estimated the relative risk compared to BYM and DC. The findings reveal that there are disparities of under-five mortality even across districts of the same region. The top ten districts with higher relative risk of under-five mortality based on model estimates are Ifakara (RR = 3.2), Nyasa ( RR = 3.0), Babati (RR = 2.74), Rungwe (RR = 2.58), Songea (RR = 2.58), Mbarali (RR = 2.55), Rorya (RR = 2.36), Namtumbo (RR = 2.36), Mbulu (RR = 2.11) and Mbogwe (RR = 2.11). The findings advocate for targeted interventions in these districts that may reduce under-five mortality and consequently increase child survival rates in Tanzania.

Published in Mathematical Modelling and Applications (Volume 11, Issue 1)
DOI 10.11648/j.mma.20261101.11
Page(s) 1-17
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

Under-five Mortality, Bayesian Hierarchical Model, Relative Risk, Small Area Estimation, Tanzania

References
[1] United Nations. (2024). Progress towards the sustainable development goals: Report of the secretary-general. Available at:
[2] Mwanga, M. K., Mirau, S. S., Quenched, J. M., and Mbalawata, I. S. (2025). Bayesian Prediction of Under-five Mortality Rates for Tanzania. Franklin Open, 10(2025): 100-221. Available at:
[3] Mwijalilege, S. A, Kadigi, M. L. and Kibiki, C. (2025). Comparing ARFIMA and ARIMA Models in Forecasting under Five Mortality Rate in Tanzania. Asian Journal of Probability and Statistics, 27(1): 107-121. Available at:
[4] Sharrow, D., Hug, L. and You, D. (2022). Global, Regional, and National Trends in Under-5 Mortality between 1990 and 2019 with Scenario-Based Projections Until 2030: A Systematic Analysis by the UN Inter-agency Group for Child Mortality Estimation. The Lancet Global Health, 10(2): 195-206. Available at:
[5] Mabula, S., Too, R. and Kerich, G. (2025). Comparative Analysis of Machine Learning Algorithms for Predicting Under-Five Mortality: Evidence from Tanzania Demographic and Health Survey. Machine Learning Research, 10(2): 110-123. Available at:
[6] UNICEF and WHO. (2024). Levels and Trends Child Mortality-Report 2023: Estimates Developed by the United Nations Inter-Agency Group for Child Mortality Estimation. Available at:
[7] NBS. (2025). Tanzania 2021-22 Demographic and Health Survey and Malaria Indicator Survey. National Bureau of Statistics, (2025). Available at:
[8] Sujon, S. H Md., Ahmmad, J., Sumon, I. H., Asif, S Md., Rahman, M. A., Manir, T. I., et al. (2025). Risk Factors of Under-five Mortality in Tanzania: Insights from the Tanzania Demographic and Health Survey 2022. BMJ Global Health, 10(7): 2025. Available at:
[9] Olusola, J. A., Oyinloye, A. A., Akeju, K. F., Ogunsakin, R. E. and Moyo, S. (2025). Spatial Analysis of Under-five Mortality in Africa using Geographically Weighted Poisson Regression. Discover Public Health, 22(1): 1-19, 2025. Available at:
[10] Li, Z., Hsiao, Y., Godwin, J., Martin, B. D., Wakefield, J., Clark, S. J., et al. (2025). Changes in the Spatial Distribution of the Under-five Mortality Rate: Small-Area Analysis of 122 DHS Surveys in 262 subregions of 35 countries in Africa. PloS one, 14(1): e0210645, 2019. Available at:
[11] Fenta, H. M., Chen, D., Zewotir, T., and Rad, N. N. (2025). Spatiotemporal Models with Confounding Effects: Application on Under-five Mortality across Four Sub-Saharan African Countries. Frontiers in Public Health, 13: 1408680, 2025. Available at:
[12] Boing, A. F., and Boing, A.C. (2025). Modest advances, persistent nequalities: child mortality in brazil from 2010 to 2022. Revista de Saude Publica, 59: e18, 2025. Available at:
[13] Mercer, L. D., Wakefield, J., Pantazis, A., Lutambi, A. M., Masanja, H., and Clark, S. (2015). Space-time Smoothing of Complex Survey Data: Small Area Estimation for Child Mortality. The annals of applied statistics, 9(4): 1889, 2015. Available at:
[14] Dwyer-Lindgren, L., Kakungu, F., Hangoma, P., Ng, M., Wang, H., Flaxman, A. D., Masiye, f., et al. (2014). Estimation of District-level Under-5 Mortality in Zambia Using Birth History Data, 1980-2010. Spatial and spatio-temporal epidemiology, 11: 89-107, 2014. Available at:
[15] Kazembe, L., Clarke, A., and Kandala, N. B.(2012). Childhood Mortality in Sub- Saharan Africa: Cross-Sectional Insight into Small-Scale Geographical Inequalities from Census Data.. BMJ open, 2(5): e001421, 2012. Available at:
[16] Amuka, E., Mitiku, A. A, and Zeru M. A. (2024). Spatiotemporal Modeling of Under-five Mortality and Associated Risk Factors in Ethiopia using 2000-2016 EDHS Data. BMC pediatrics, 24(1): 201, 2024. Available at:
[17] Tesema, G. A., Teshale, A. B., and Tessema, Z. T. (2021). Incidence and Predictors of Under-five Mortality in East Africa Using Multilevel Weibull Regression Modeling. Archives of Public Health, 79(1): 196, 2021. Available at:
[18] Sokadjo, Y. M., Atchade, M. N., and Kossou, H. D.(2020). Carbon Dioxide Emissions from Transport and Anemia Influence on Under-five Mortality in Benin. Environmental Science and Pollution Research, 27(32): 40277-40285, 2020. Available at:
[19] Aheto, J. M. (2019). Predictive Model and Determinants of Under-five Child Mortality: Evidence from the 2014 Ghana Demographic and Health Survey. BMC public health, 19: 1-10, 2020. Available at:
[20] Yoo, E., Palermo, T., Maluka, S. (2021). Geostatistical linkage of national demographic and health survey data: a case study of Tanzania. Population Health Metrics, 19: 42, October 2021. Available at:
[21] Burgert, C.R., Prosnitz, D. (2014). Linking DHS Household and SPA Facility Surveys: Data Considerations and Geospatial Methods. United States Agency for International Development, DHS Spatial Analysis Reports No. 10, September 2014. Available at:
[22] Lee, S., Kim, Y., Ji, B., and Kim, Y. (2025). Addressing Missing Data in Slope Displacement Monitoring: Comparative Analysis of Advanced Imputation Methods. Buildings, 15(2): 236, January 2025. Available at:
[23] Zang, L. and Xiong, F. (2025). Harnessing Machine Learning to Address High Levels of Missing Data in Cross-National Studies: From Bias to Precision in Public Service Research. Journal of Comparative Policy Analysis: Research and Practice, pages 1-21, April 2025. Available at:
[24] Popovich, D. (2025). How to Treat Missing Data in Survey Research. Journal of Marketing Theory and Practice, 33(1):43-59, July 2025. Available at:
[25] Camillier, G. (2025). Missing Data and Imputation. In Introduction to Surgical Trials, Springer, pages 131-141, February 2025. Available at:
[26] Moraga, P. (2023). Spatial Statistics for Data Science: Theory and Practice with R. New York: Chapman and Hall/CRC, Available at:
[27] Ashwin, J. and Scott, A. (2025). A Bayesian Model of Later Life Mortality Trends and Implications for Longevity. Journal of the Royal Statistical Society Series A: Statistics in Society, pages 1-17, 2025. Available at:
[28] Jahan, F., Kennedy, D. W., Duncan, E. W., and Mengersen, K. L. (2022). Evaluation of Spatial Bayesian Empirical Likelihood Models in Analysis of Amall Area Data. PloS one, 17(5): e0268130, 2022. Available at:
[29] Fenta, H. M., Chen, D., Zewotir, T. T., Rad, N. N., Belay, D. B., and Yilema, S. A. (2025). Comparisons of Cox Semi-Parametric and Parametric Shared Frailty Models: Application for Under-five Children Survival in Sub-Saharan Africa. BMC public health, 25(1): 2884, 2025. Available at:
[30] Mahmoud , F. F. H., and Kim, I. (2024). Semi-parametric Change Points Detection Using Single Index Spatial Random Effects Model in Environmental Epidemiology Study. PloS one, 19(12): e0315413, 2024. Available at:
[31] Rue , H., Martino, S., and Chopin, N. (2009). Approximate Bayesian Inference for Latent Gaussian Models by Using Integrated Nested Laplace Approximations. Journal of the Royal Statistical Societ, 71(2): 319-392, 2009. Available at:
[32] Vicente, G., Goicoa, T., and Ugarte, M. D. (2020). Bayesian Inference in Multivariate Spatio-temporal Areal Models Using INLA: Analysis of Gender-based Violence in Small Areas. Stochastic Environmental Research and Risk Assessment, 34(10): 1421-1440, 2020. Available at:
[33] Lee, D. (2013). CARBayes: An R Package for Bayesian Spatial Modeling with Conditional Autoregressive Priors. Journal of Statistical Software, 55(2013): 1-24, 2013. Available at:
[34] Kholuenetale, M., Wegbom, A. I., Tudeme, G., and Onikan, A. (2020). Household Factors Associated with Infant and Under-five Mortality in Sub-Saharan Africa Countries. International Journal of Child Care and Education Policy, 14(1): 10, 2020. Available at:
[35] NBS. (2025). Mortality and health. Technical Report. Dar es Salaam: National Bureau of Statistics, (2025). Available at:
[36] Ward, Z. J., Atun, R., King, G., Dmello, B. S., and Goldie, S. J. (2024). Global Maternal Mortality Projections by Urban/Rural Location and Education Level: A Simulation-based Analysis. EClinicalMedicine, 72, 2024. Available at:
[37] Riebler, A., Sarbye, S. H., Simpson, D., and Rue, H. (2016). An Intuitive Bayesian Spatial Model for Disease Mapping that Accounts for Scaling. Statistical Methods in Medical Research, 25(4): 1145-1165, 2016. Available at:
[38] MoF and NBS. (2017). Mbarali District Council: Socio-Economic Profile 2015. Mbeya: National Bureau of Statistics, (2017). Available at:
[39] Magoti, E. (2025). Ending Hunger in Tanzania: Investigating the Impact of Agricultural Preharvest Losses on Food Security. Unpublised PhD Thesis, University of Dar es Salaam.
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  • APA Style

    Mabula, S., Too, R., Kerich, G. (2026). Small Area Risk Mapping of Under-five Mortality: A District-level Analysis using Parametric Approach. Mathematical Modelling and Applications, 11(1), 1-17. https://doi.org/10.11648/j.mma.20261101.11

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    Mabula, S.; Too, R.; Kerich, G. Small Area Risk Mapping of Under-five Mortality: A District-level Analysis using Parametric Approach. Math. Model. Appl. 2026, 11(1), 1-17. doi: 10.11648/j.mma.20261101.11

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    AMA Style

    Mabula S, Too R, Kerich G. Small Area Risk Mapping of Under-five Mortality: A District-level Analysis using Parametric Approach. Math Model Appl. 2026;11(1):1-17. doi: 10.11648/j.mma.20261101.11

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  • @article{10.11648/j.mma.20261101.11,
      author = {Salyungu Mabula and Robert Too and Gregory Kerich},
      title = {Small Area Risk Mapping of Under-five Mortality: A District-level Analysis using Parametric Approach
    },
      journal = {Mathematical Modelling and Applications},
      volume = {11},
      number = {1},
      pages = {1-17},
      doi = {10.11648/j.mma.20261101.11},
      url = {https://doi.org/10.11648/j.mma.20261101.11},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.mma.20261101.11},
      abstract = {Mortality of under-five children remains a pressing public health concern in Tanzania, with spatial disparities contributed by the intersection of socioeconomic, health and environmental factors. This study employs Bayesian techniques and epidemiological spatial methods to estimate and map district-level under-five mortality, focusing on malaria prevalence, maternal education and source of drinking water. The districts with high risk are identified using georeferenced data of under-five mortality from recent Tanzania Demographic and Health Survey. We estimated the relative risk (RR) of under-five mortality within a hierarchical Bayesian spatial framework using three priors namely Besang-York-Mollie (BYM), Dean & Cressie (DC) and Leroux (BMY2). The model performance was evaluated using Watanabe-Akaike Information criterion (WAIC) to identify the best, from which the relative risk of under-five mortality was estimated and visualized using interactive and static maps. The Leroux (BYM2) model effectively estimated the relative risk compared to BYM and DC. The findings reveal that there are disparities of under-five mortality even across districts of the same region. The top ten districts with higher relative risk of under-five mortality based on model estimates are Ifakara (RR = 3.2), Nyasa ( RR = 3.0), Babati (RR = 2.74), Rungwe (RR = 2.58), Songea (RR = 2.58), Mbarali (RR = 2.55), Rorya (RR = 2.36), Namtumbo (RR = 2.36), Mbulu (RR = 2.11) and Mbogwe (RR = 2.11). The findings advocate for targeted interventions in these districts that may reduce under-five mortality and consequently increase child survival rates in Tanzania.
    },
     year = {2026}
    }
    

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    T1  - Small Area Risk Mapping of Under-five Mortality: A District-level Analysis using Parametric Approach
    
    AU  - Salyungu Mabula
    AU  - Robert Too
    AU  - Gregory Kerich
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    AB  - Mortality of under-five children remains a pressing public health concern in Tanzania, with spatial disparities contributed by the intersection of socioeconomic, health and environmental factors. This study employs Bayesian techniques and epidemiological spatial methods to estimate and map district-level under-five mortality, focusing on malaria prevalence, maternal education and source of drinking water. The districts with high risk are identified using georeferenced data of under-five mortality from recent Tanzania Demographic and Health Survey. We estimated the relative risk (RR) of under-five mortality within a hierarchical Bayesian spatial framework using three priors namely Besang-York-Mollie (BYM), Dean & Cressie (DC) and Leroux (BMY2). The model performance was evaluated using Watanabe-Akaike Information criterion (WAIC) to identify the best, from which the relative risk of under-five mortality was estimated and visualized using interactive and static maps. The Leroux (BYM2) model effectively estimated the relative risk compared to BYM and DC. The findings reveal that there are disparities of under-five mortality even across districts of the same region. The top ten districts with higher relative risk of under-five mortality based on model estimates are Ifakara (RR = 3.2), Nyasa ( RR = 3.0), Babati (RR = 2.74), Rungwe (RR = 2.58), Songea (RR = 2.58), Mbarali (RR = 2.55), Rorya (RR = 2.36), Namtumbo (RR = 2.36), Mbulu (RR = 2.11) and Mbogwe (RR = 2.11). The findings advocate for targeted interventions in these districts that may reduce under-five mortality and consequently increase child survival rates in Tanzania.
    
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