Browsing by Author "Mbwambo, Sauda Hatibu"

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    Rating of cash crop insurance contracts in Tanzania using nonparametric methods
    (IGI Global, 2021) Massawe, Expery Mathias; Kirigiti, Peter Josephat; Mbwambo, Sauda Hatibu
    This chapter used nonparametric methods to establish the parameters of cash crop insurance contracts based on zone yields. The secondary historical yields data obtained from the Food and Agriculture Organization of the United Nations, for the period of 1961 through 2018, for cotton and cashew nuts, were used both in estimating the kernel density function and forecasting the mean yield. The estimated kernel density and mean forecasts were used to tabulate, at a different level of coverage, the probability of loss, the expected yield shortfall (kilogram per hectare, denote kg/ha), and the actuarial-fair premium rates for each crop. The results showed that, at different levels of coverage (i.e., from 50% to 90%), the actuarial-fair premium rates range between 0% and 32% of the sum assured. However, the range for cashew nuts is narrow (0% to 8%) while that of cotton is 4% to 32%, a very wider range compared to cashew nuts. Further, the expected losses for cotton, in the same coverage intervals, ranges from 11.58kg/ha to 256.06kg/ha while that of cashew was 0.44kg/ha to 19.69kg/ha.
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    Socio-environmental predictors of diabetes incidence disparities in Tanzania mainland: a comparison of regression models for count data
    (Springer Science and Business Media LLC, 2024) Mbwambo, Sauda Hatibu; Mbago, Maurice C.; Rao, Gadde Srinivasa
    Abstract Background Diabetes is one of the top four non-communicable diseases that cause death and illness to many people around the world. This study aims to use an efficient count data model to estimate socio-environmental factors associated with diabetes incidences in Tanzania mainland, addressing lack of evidence on the efficient count data model for estimating factors associated with disease incidences disparities. Methods This study analyzed diabetes counts in 184 Tanzania mainland councils collected in 2020. The study applied generalized Poisson, negative binomial, and Poisson count data models and evaluated their adequacy using information criteria and Pearson chi-square values. Results The data were over-dispersed, as evidenced by the mean and variance values and the positively skewed histograms. The results revealed uneven distribution of diabetes incidence across geographical locations, with northern and urban councils having more cases. Factors like population, GDP, and hospital numbers were associated with diabetes counts. The GP model performed better than NB and Poisson models. Conclusion The occurrence of diabetes can be attributed to geographical locations. To address this public health issue, environmental interventions can be implemented. Additionally, the generalized Poisson model is an effective tool for analyzing health information system count data across different population subgroups.
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    Statistical quality control and reliability estimation based on exponentiated inverse rayleigh distribution
    (The University of Dodoma, 2018) Mbwambo, Sauda Hatibu
    This research gives some statistical quality control techniques and reliability estimation based on exponentiated inverse Rayleigh distribution (EIRD) which can be applied in different industries so as to improve the quality of their products. EIRD has been obtained through generalization process and its mathematical properties were discussed. Estimation of unknown parameters was done by using maximum likelihood method, least square method, weighted least square and percentile estimation method. The methods were compared by using Monte Carlo simulation approach based on the values of bias and MSE, the results show that ML performs well. Further, the estimation of single component stress-strength reliability and multi-component stress-stress reliability was done, confidence intervals of reliability were also obtained and the results show that the methods perform. An attribute control chart is also developed for EIRD under a time truncated life test. The performance of the proposed chart is discussed using average run length (ARL). A simulation study is carried out to obtain the performance of the proposed control chart for monitoring non-conforming items. The results show that the chart is effective in detecting any shift happens in the process. Also Shewhart individual control chart is developed to check whether the data used are in control state or not by using. The results show that the data are not in control.