Conference Presentations by George Orwa
Neglecting Urbanization would be shattering as it is directly comparative to development of a cou... more Neglecting Urbanization would be shattering as it is directly comparative to development of a country. Effect of an ever rising population growth in the era of globalization is compounded by a speedily accelerating relocation from rural areas to the urban centers. These accelerated pace of urbanization has led to employment problems. Urban labour force balloons’ faster than the employment created in the urban sector of economy e.g. manufacturing and services sector. So urban centers are not able to supply employment to all labour force, in formal jobs, looking forward for opportunities for earning their living, so, they are forced to find other opportunities in informal sector of urban settlement
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The non-formal sector represents a vital part of the economy and the labour market in many jurisdictions, especially in developing nations. It plays an important role in employment creation, production, and income generation. Within this informal sector of workforce, street vendors play an important role in employing migrated populace. Vending in urban area is categorized by ease of access, small scale of business carried out in temporary structure in a variable location without a fixed place or store. Vendors sell their products in unregulated and competitive market environment without observing any predetermined hours for vending. Very often, vending is on an illegal basis converse to the government convention; it does not depend upon formal financial institutions for its credit needs.
As initial capital and risk associate for vending daily needs is low, but due to this street vendor’s large number of problems associated with land use, security, health and infrastructure social arise. We have identified Lower side of Moi Avenue Street as study area and studied the problems. The paper provides spatial solutions for Lower side of Moi Avenue street and policy measures for regulating urban vendors in other settlements too.
Papers by George Orwa
Misspecification of frailty random effects in a clustered survival data
Journal of Statistical and Econometric Methods, 2019
Survival analysis models the time it takes until an event occurs. The prototypical event is deat... more Survival analysis models the time it takes until an event occurs. The prototypical event is death, from which the name survival analysis is derived.Accordingly, each time survival analysis is studied, aspects of some selected rates or reliability of some study are usually considered. Frailty modelling has been used in this study as the statistical tool for analysing the time-event data. Parametric and non-parametric models and the frailty models are tted to help derive the required con-clusions.The impact of misspeci cation of frailty random effects in a survival data using parametric frailty modelling approach were determined during this research study.It is expected that these approaches would produce less bias estimates compared to the results achieved of the estimates when the misspeci cation of the frailty random effects are ignored.Mathematics Subject Classi fication :62H30Keywords: misspeci cation, frailty modeling, clustered data.
Influence of Marketing Promotions Strategy on Performance of the Tea Industry in Mount Kenya Region
African Journal of Emerging Issues, Apr 9, 2019
The study examines the moderating effect of CEO tenure and managerial experience on firm specific... more The study examines the moderating effect of CEO tenure and managerial experience on firm specific determinants of corporate cash holdings among private manufacturing firms in Kenya. The research employed the upper echelons theory to identify CEO characteristics that are linked to various organizational processes and outcomes such as cash holding. This survey-based study selected a sample of 156 private manufacturing firms from the firms registered with the KAM that are located in Nairobi and surrounding area using stratified random sampling technique. The research collected primary data using selfadministered questionnaires to gather self-reported financial measures from the CFOs. The study employed stepwise multiple regression analysis to determine the moderating effect of CEO tenure and managerial experience on independent and dependent variables. The study concludes that the CEO tenure significantly moderates firm size, growth opportunities, and likelihood of financial distress as determinants of corporate cash holdings. Further, the study concludes that CEO managerial experience in other industries significantly moderates firm size and cash flow volatility determinants of corporate cash holdings among private manufacturing firms in Kenya.
Currency crisis is classified as one of the top ranked extreme risks of the third millennium. It ... more Currency crisis is classified as one of the top ranked extreme risks of the third millennium. It becomes a serious financial and economic problem worldwide and researchers have focused their attention on understanding how those crises are studied, modeled and analyzed. These currency crises exist in the form of speculative attacks in the foreign exchange market. These speculative pressures are measured by crisis indexes named exchange market pressure indexes (EMPI), which need to reflect both successful and unsuccessful speculative pressures on local currency. This paper aims to develop an alternative exchange market pressure index model for currency crisis. The methodology that will be adopted to construct the alternative EMP index model is the "EMPI model independent based approach". A simulation analysis is also performed to validate and verify the theoretical properties of the proposed EMPI model. We end up by studying the different properties related to the EMPI model. This new alternative EMPI model is expected to measures incidence of currency crisis periods in a regional or/and global economies (countries), to measure also incidence for currency crisis for successful and unsuccessful attacks and identify currency crisis happening either in a fixed, floating and/or intermediate exchange regimes. Our investigation suggests that the exchange market pressure index similar to other financial time series tends to be heavy tailed. Overall, the results appear to confirm that the EMPI is stationary and again correlated. A comparison study on Dollar and Euro Kenya's EMPIs is conducted and results reveal a very weak difference between them.
International Journal of Statistics and Probability, Jun 26, 2017
This paper provides a complete proof of the strong convergence of the Jump adapted discretization... more This paper provides a complete proof of the strong convergence of the Jump adapted discretization Scheme in the univariate and mark independent jump diffusion process case. We put in detail and clearly a known and general result for mark dependent jump diffusion process. A Monte-Carlo simulation is used as well to show numerical evidence.
The collected data was analyzed by use of statistical tools for data analysis namely, MS-Excel an... more The collected data was analyzed by use of statistical tools for data analysis namely, MS-Excel and SPSS. Finally, the researcher prepared a report by drawing conclusions and suggesting major recommendations based on the study findings.
PLOS ONE, Mar 1, 2019
Visceral Leishmaniasis is a very dangerous form of leishmaniasis and, shorn of appropriate diagno... more Visceral Leishmaniasis is a very dangerous form of leishmaniasis and, shorn of appropriate diagnosis and handling, it leads to death and physical disability. Depicting the spatiotemporal pattern of disease is important for disease regulator and deterrence strategies. Spatiotemporal modeling has distended broad veneration in recent years. Spatial and spatiotemporal disease modeling is extensively used for the analysis of registry data and usually articulated in a hierarchical Bayesian framework. In this study, we have developed the hierarchical spatiotemporal Bayesian modeling of the infected rate of Visceral leishmaniasis in Human (VLH). We applied the Stochastics Partial Differential Equation (SPDE) approach for a spatiotemporal hierarchical model for Visceral leishmaniasis in human (VLH) that involves a GF and a state process is associated with an autoregressive order one temporal dynamics and the spatially correlated error term, along with the effect of land shield, metrological, demographic, socio-demographic and geographical covariates in an endemic area of Amhara regional state, Ethiopia. The model encompasses a Gaussian Field (GF), affected by an error term, and a state process described by a first-order autoregressive dynamic model and spatially correlated innovations. A hierarchical model including spatially and temporally correlated errors was fit to the infected rate of Visceral leishmaniasis in human (VLH) weekly data from January 2015 to December 2017 using the R package R-INLA, which allows for Bayesian modeling using the stochastic partial differential equation (SPDE) approach. We found that the mean weekly temperature had a significant positive association with infected rate of VLH. Moreover, net migration rate, clean water coverage, average number of households, population density per square kilometer, average number of persons per household unit, education coverage, health facility coverage, mortality rate, and sex ratio had a significant association with the infected rate of visceral leishmaniasis (VLH) in the region. In this study, we investigated the dynamic spatiotemporal modeling of Visceral leishmaniasis in Human (VLH) through a stochastic partial differential equation approach (SPDE) using integrated nested Laplace approximation (INLA). Our study had confirmed both metrological, demographic, sociodemographic and geographic covariates
International Journal of Research In Business and Social Science, 2020
This study aimed at investigating the effect of organizational culture and strategy implementatio... more This study aimed at investigating the effect of organizational culture and strategy implementation process of Private chartered universities in Kenya. The cross-sectional survey research design was adopted and it used both quantitative and qualitative data as it seeks the effect of organizational culture on the implementation of corporate strategy. The accessible population included Registrars, Deans, Directors, Heads of Departments, academic staff, and students' leaders. This study used both stratified random sampling and the target sample size was 198 employees. The statistical package for social sciences (SPSS) version 21 was used to analyze data. The competing values framework was adopted to identify the organizational culture types that are displayed in Private chartered universities. A multiple linear regression model was also used to derive inferential statistical indicators. Normality testing was done to compare the cumulative distribution of the data with the expected cumulative normal distribution and it bases its P value on the largest discrepancy. Two versions of Breusch-Pagan tests were conducted to test the null hypothesis on whether heteroscedasticity or homoscedasticity was present. Based on the regression analysis it was clear that the null hypothesis was rejected and the alternative hypothesis accepted. The conclusion was that Clan culture had a significant influence on the strategy implementation process of Private chartered universities in Kenya. The results established that there was a linear positive relationship between Clan culture and strategy implementation which implies that an increase in Clan culture would lead to a linear increase in Strategy implementation in Private chartered universities in Kenya.
International journal of data science and analysis, 2020
A Bayesian Self-Controlled Case-Series (BSCCS) method is proposed and used to estimate the relati... more A Bayesian Self-Controlled Case-Series (BSCCS) method is proposed and used to estimate the relative risk of an adverse drug event (ADE) given transient exposure to a drug or vaccine. Markov Chain Monte Carlo (MCMC) methods through WinBUGS are used to estimate parameters of the model given different settings and sample sizes. The method explores full posterior distribution for the model to obtain the relative risk estimates which at times is a challenge in likelihood analysis of complex models. Data was simulated for 10, 20 or 50 children aged between 365 and 730 days, and received their first dose of the measles, mumps, and rubella (MMR) vaccine within this follow-up period. Each child had the outcome event-viral-meningitis, in the follow-up period. Results of the data analysis indicated an increased risk of viral meningitis within 14-35 days post vaccination. Results of Bayesian approach are quite similar to the MLE risk estimates, assuming a non-informative prior. However, with more informative priors, BSCCS method produced better results with narrow credible intervals. For the real data, children aged 365 and 730 days, exposed to MMR vaccine, with viral meningitis (single exposure) were considered. While the frequentist approach estimated the incidence rate ratio (IRR) as IRR 12.037 (95% CI (3.002-48.259)), the Bayesian estimate was IRR 8.971 (95% CI 2.869-27.994). This is similar to the MLE results but with narrow credible intervals. In all cases, there is significantly higher risk of viral meningitis within 14-35 days post MMR vaccination. Results from the simulation study and real data revealed that the BSCCS model fitted better than the SCCS model.
Markov Transition Matrices For Cohorts Of Students (JKUAT)
LAP LAMBERT Academic Publishing eBooks, May 31, 2017
Higher Education Instutions in Kenya have encounterd rapid expansion of programs, departments in ... more Higher Education Instutions in Kenya have encounterd rapid expansion of programs, departments in the recent years and this has profound impact on the entire society.This continues to demand a greater proportion of the country’s financial resources and the cost is borne solely by the Government.As result of this events much of the attention centres on the lag between the time students are admitted and the time they are graduating.The purpose of this research is to investigate the flow of students in the BSc.physical Science programme in JKUAT via Marcov analysis.A sample of BSc.Actuarial Science 2005 and 2006 cohort was used. A transition model that is used here describes the stocks and flows of students through an education system in terms of transition ratios.The results show that under fairly general Markov chain model of the transitional determination, student flows do not display the random walk characteristics which may be interpreted as purely following a Markov process.
Mathematical theory and modeling, 2014
Regional disparity in literacy levels must be addressed if Kenya is to achieve its international ... more Regional disparity in literacy levels must be addressed if Kenya is to achieve its international goals such as Education for All (EFA) and Millennium Development Goals (MDG). Literacy level in Kenya has been on the rise. However, the 2007 Kenya National Literacy Survey crude rates showed that on average 38.5 per cent (7.8 million) of Kenya's adult population was illiterate with significant regional and gender variation. Bayesian binary logistic models (with and without CAR spatial and unstructured random effects) are applied to the Kenya National Adult Literacy Survey (2007) data that was obtained from sampled 18000 households, 4782 in urban and 10914 in rural areas, to investigate spatial variation of illiteracy levels in Kenya. There were 15734 successful interviews that were comprised of 6493 were male and 9241 female The best fitted model was found to be the CAR model with age, sex, disability and awareness of adult literacy programs as the significant explanatory variables. Smoothed map of illiteracy from the best fitted model was then produced together with its corresponding confidence interval maps for regional variation in Kenya, in order to capture visual uncertainty in estimation. These maps can be used by policy makers to identify the pattern and tailor make programs appropriate for each region.
American Journal of Mathematics and Statistics, 2018
The focus of this study is to fit a model that ranks commercial banks in Kenya, according to thei... more The focus of this study is to fit a model that ranks commercial banks in Kenya, according to their specific financial status. The second focus of this study is to use dimensionally reduced financial distress determinants. Secondary data in audited bank financial statements from the Nairobi Stocks Exchange (NSE) report 2016/2017, and other statements available from bank websites used for the fitting of the model. In total, 17 banks were sampled. 10 explanatory variables were used to analyze the linkage between bank specific factors and economic factors majorly associated with bank fragility. The data obtained was cleaned, coded and the required statistical outputs generated using R for Windows statistical package. Principal component analysis (PCA) was employed in dimension reduction. A multiple logit regression model was fitted to the collected data. The most significant determinants of bank fragility were found to be bank size and profit before tax. Using the derived logit model, it was determined that Kenya Commercial Bank (KCB), Equity Bank and Cooperative Bank were the top three banks in terms of financial strength. Their probabilities of staying up were 1.000, 0.999 and 0.985 respectively. The bottoms two were Chase Bank (0.125) and Imperial Bank (0.037). These two were under receivership during this study.
An Extended Kumaraswamy-Gull Alpha Power Exponential Distribution: Properties and Application to Real Data
International Journal of Mathematics Trends and Technology, Aug 30, 2022
The Gamma Inverse Weibull Poisson Distribution with Application to Survival Data
Advances and applications in statistics, Dec 10, 2019
International Journal of Statistics and Probability, Apr 27, 2019
This study explores the estimation of finite population total. For many years design-based approa... more This study explores the estimation of finite population total. For many years design-based approach dominated the scene in statistical inference in sample surveys. The scenario has since changed with emergence of the other approaches (Model-Based, Model-Assisted and the Randomization-Assisted), which have proved to rival the conventional approach. This paper focuses on a model based approach. Within this framework a nonparametric regression estimator for finite population total is developed. The nonparametric technique has been found from previous studies to be advantageous than its parametric counterpart in terms of robustness and flexibility. Kernel smoother has been used in construction of the estimator. The challenge of the boundary problem encountered with the Nadaraya-Watson estimator has been addressed by modifying it using reflection technique. The performance of the proposed estimator has been compared to the design-based Horvitz Thompson estimator and the model-based nonparametric regression estimator proposed by (Dorfman, 1992) and the ratio estimator using simulated data.
International journal of academic research in business & social sciences, Apr 3, 2016
Corporate entrepreneurship is the process of generating, developing and implementing new ideas an... more Corporate entrepreneurship is the process of generating, developing and implementing new ideas and behaviors by a company. The environment that business operates is volatile intensifying global competition and rapid technological progress. Better quality and service are no longer enough to give competitive advantage. However once companies embrace corporate entrepreneurship it influences competitive advantage. The need for corporate entrepreneurship has arisen from a variety of environmental pressing problems including, required changes, innovations, and improvements in the market place to avoid stagnation and decline. Therefore this study sought to investigate the effect of corporate entrepreneurship determinants in the performance of food fortification companies in Kenya. The study was conducted using descriptive method. Statistical population included managers and employees of food fortification industries. Data was collected using questionnaires. Statistical population included managers and employees of food fortification companies. From the study, it was found out that organizations should have clear policies, goals and objectives supports performance in food fortification companies. Also, it was found out that, rewards incentive given to employees who come up with new products promotes performance in fortification companies in Kenya which was highly rated. Finally, it was found out that corporate entrepreneurial management and Corporate entrepreneurial incentives increase performance in food fortification companies in Kenya.
A Reduced Form of the Three Factor Commodity Derivative Valuation Model
use of statistical tools for data analysis known as SPSS. A report was compiled by drawing conclu... more use of statistical tools for data analysis known as SPSS. A report was compiled by drawing conclusions and suggesting major recommendations based on the study findings.
International Journal of Advanced Research in Management and Social Sciences, Apr 1, 2015
The purpose of this study was to investigate the managerial perspectives on the firm characterist... more The purpose of this study was to investigate the managerial perspectives on the firm characteristics and corporate cash holdings among in private manufacturing firms in Kenya. Several international studies show that companies retain important cash holdings. Yet, the prevalent questions have been: Why do firms hold huge amount of cash? Is there an optimum level of cash holdings? A review of the extant literature reveals that mostly the current studies depend on secondary data to provide evidence on corporate cash holdings. This survey-based study sought to bridge this gap in the literature by examining chief finance officers of private manufacturing firms to comprehensively investigate the corporate cash holdings from a managerial perspective. A sample of 156 firms was selected for the survey using stratified random sampling technique from which 117 questionnaires were returned. The primary data was sourced through personally administered survey questionnaires to the chief finance officers. Data was analyzed using descriptive statistics and inferential statistics (independent sample t-test). The study concludes that CFOs of private manufacturing firms in Kenya are of the view that growth opportunities, leverage and debt structure, firm size, likelihood of financial distress and cash flow variability are all important drivers of corporate cash holding policy.
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Conference Presentations by George Orwa
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The non-formal sector represents a vital part of the economy and the labour market in many jurisdictions, especially in developing nations. It plays an important role in employment creation, production, and income generation. Within this informal sector of workforce, street vendors play an important role in employing migrated populace. Vending in urban area is categorized by ease of access, small scale of business carried out in temporary structure in a variable location without a fixed place or store. Vendors sell their products in unregulated and competitive market environment without observing any predetermined hours for vending. Very often, vending is on an illegal basis converse to the government convention; it does not depend upon formal financial institutions for its credit needs.
As initial capital and risk associate for vending daily needs is low, but due to this street vendor’s large number of problems associated with land use, security, health and infrastructure social arise. We have identified Lower side of Moi Avenue Street as study area and studied the problems. The paper provides spatial solutions for Lower side of Moi Avenue street and policy measures for regulating urban vendors in other settlements too.
Papers by George Orwa
.
The non-formal sector represents a vital part of the economy and the labour market in many jurisdictions, especially in developing nations. It plays an important role in employment creation, production, and income generation. Within this informal sector of workforce, street vendors play an important role in employing migrated populace. Vending in urban area is categorized by ease of access, small scale of business carried out in temporary structure in a variable location without a fixed place or store. Vendors sell their products in unregulated and competitive market environment without observing any predetermined hours for vending. Very often, vending is on an illegal basis converse to the government convention; it does not depend upon formal financial institutions for its credit needs.
As initial capital and risk associate for vending daily needs is low, but due to this street vendor’s large number of problems associated with land use, security, health and infrastructure social arise. We have identified Lower side of Moi Avenue Street as study area and studied the problems. The paper provides spatial solutions for Lower side of Moi Avenue street and policy measures for regulating urban vendors in other settlements too.