Department of Statistics
Permanent URI for this collectionhttp://197.255.125.131:4000/handle/123456789/23133
Browse
11 results
Search Results
Item Perceived antimicrobial dispensing practices in medicine outlets in Ghana: A maximum difference experiment design(PLOS ONE, 2023) Nyarko, E.; Akoto, F.M.; Doku-Amponsah, K.Introduction Antimicrobials are consumed among patients globally, but in developing and middle-income countries, these drugs can be obtained without a prescription from pharmacies and licensed drug stores due to inadequate regulation in the pharmaceutical sector. This study aimed to assess antimicrobial dispensing practices in medicine sales outlets (i.e., pharmacies and licensed drug stores) to provide quantitative evidence for policy discussions to enhance patient safety and care quality in Ghana’s pharmaceutical industry. Method The data for this study were obtained from a cross-sectional survey conducted in the Greater Accra region between July and August 2022. The survey was conducted through interviewer-administered questionnaires, and 200 staff members from medicine sales out lets were randomly selected using a two-stage cluster and random sampling technique. The maximum difference experiment model, rooted in random utility theory, was used to analyze their antimicrobial dispensing practices. Result We found that medicine sales outlet staffs were highly concerned about following the drug act and not dispensing antimicrobials without a prescription, and usually refer a patient to get a prescription from a doctor if the patient has complications (like high fever, generalized malaise, fatigue as symptoms, sinusitis). Stronger concerns were also observed for medi cine outlet staff not dispensing antimicrobials without a prescription if the patient is pediatric or geriatric with a severe infection. They also evaluated patients and dispensed antimicrobi als based on symptoms, not their age or gender. However, they tended not to dispense anti biotics if the patient had a mild fever and requested it without a prescription Conclusion Our results provide insight into the need for a national surveillance system for monitoring antimicrobial prescribing and dispensing practices at medicine sales outlets. Therefore, the selection of antimicrobials for treating infectious diseases may be informed by evidence based antimicrobial prescribing and dispensing surveillance data and will help policymakers to know the pattern of commonly consumed antimicrobials in the medicine sales outlets.Item Approximate and Exact Optimal Designs for Paired Comparison Experiments(Calcutta Statistical Association Bulletin, 2022) Nyarko, E.; Doku-Amponsah, K.In this article, the problem of finding optimal paired comparison approximate and exact designs for the identification of main effects and two and three and four attribute interactions, when the alternatives are characterized by either full profiles or partial profiles, is considered. The resulting designs are also optimal under the indifference assumption of equal choice probabilities for a multinomial logit model when the choice sets are pairs.Item Evaluation of the DWT-PCA/SVD Recognition Algorithm on Reconstructed Frontal Face Images(Hindawi, 2021) Asiedu, L.; Essah, B.O.; Iddi, S.; Doku-Amponsah, K.; Mettle, F.O.The face is the second most important biometric part of the human body, next to the finger print. Recognition of face image with partial occlusion (half image) is an intractable exercise as occlusions affect the performance of the recognition module. To this end, occluded images are sometimes reconstructed or completed with some imputation mechanism before recognition. This study assessed the performance of the principal component analysis and singular value decomposition algorithm using discrete wavelet transform (DWT-PCA/SVD) as preprocessing mechanism on the reconstructed face image database. The reconstruction of the half face images was done leveraging on the property of bilateral symmetry of frontal faces. Numerical assessment of the performance of the adopted recognition algorithm gave average recognition rates of 95% and 75% when left and right reconstructed face images were used for recognition, respectively. It was evident from the statistical assessment that the DWT-PCA/SVD algorithm gives relatively lower average recognition distance for the left reconstructed face images. DWT-PCA/SVD is therefore recommended as a suitable algorithm for recognizing face images under partial occlusion (half face images). The algorithm performs relatively better on left reconstructed face images.Item Modeling the Amount of Waste Generated by Households in the Greater Accra Region Using Artificial Neural Networks(Hindawi, 2021) Chapman-Wardy, C.; Asiedu, L; Doku-Amponsah, K.; Mettle, F.O.Waste can be defined as solids or liquids unwanted by members of the society and meant to be disposed. In developing countries such as Ghana, the management of waste is the responsibility of the metropolitan authorities. These authorities do not seem to have effective management of the waste situation, and therefore, it is not unusual to see waste clog the drains and litter the streets of the capital city, Accra. )e impact of waste on the environment, along with its associated health-related problems, cannot be overemphasized. )e Joint Monitoring Programme report in 2015 ranked Ghana as the seventh dirtiest country in the world. )e lack of effective waste management planning is evident in the large amount of waste dumped in open areas and gutters that remains uncollected. In planning for solid waste management, reliable data concerning waste generation, influencing factors on waste generation, and a reliable forecast of waste quantities are required. )is study used two algorithms, namely, Lev enberg–Marquardt and the Bayesian regularization, to estimate the parameters of an artificial neural network model fitted to predict the average monthly waste generated and critically assess the factors that influence solid waste generation in some selected districts of the Greater Accra region. )e study found Bayesian regularization algorithm to be suitable with the minimum mean square error of 104.78559 on training data and 217.12465 on test data and higher correlation coefficients (0.99801 on training data, 0.99570 on test data, and 0.99767 on the overall data) between the target variables (average monthly waste generated) and the predicted outputs. House size, districts, employment category, dominant religion, and house type with respective importance of 0.56, 0.172, 0.061, 0.027, and 0.026 were found to be the top five important input variables required for forecasting household waste. It is recommended that efforts of the government and its stakeholders to reduce the amount of waste generated by households be directed at providing bins, increasing the frequency of waste collection (especially in highly populated areas), and managing the economic activities in the top five selected districts (Ledzekuku Krowor, Tema West, Asheidu Keteke, Ashaiman, and Ayawaso West), amongst others.Item Joint large deviation principle for some empirical measures of the d-regular random graphs(Taylor & Francis Group, 2021) Ibrahim, U.; Lotsi, A.; Doku-Amponsah, K.In this paper, we define a d–regular random model by perfect matching of vertices or paring of vertices. For each vertex, we assign a q–state spin. From this d–regular graph model, we define the empirical co-operate measure, which enumerates the number of co-operation between a given couple of spins, and empirical spin measure, which enumerates the number of sites having a given spin on the d–regular random graph model. For these empirical measures, we obtain large deviation principle(LDP) in the weak topology.Item Asymptotics of the Partition Function of Ising Model on Inhomogeneous Random Graphs(Far East Journal of Mathematical Sciences, 2017-12) Doku-Amponsah, K.For a finite random graph, we defined a simple model of statistical mechanics. We obtain an annealed asymptotic result for the random partition function for this model on finite random graphs as $n,$ the size of the graph is very large. To obtain this result, we define the \emph{ empirical bond distribution}, which enumerates the number of bonds between a given couple of spins, and \emph{ empirical spin distribution}, which enumerates the number of sites having a given spin on the spinned random graphs. For these empirical distributions we extend the large deviation principle(LDP) to cover random graphs with continuous colour laws. Applying Varandhan Lemma and this LDP to the Hamiltonian of the Ising model defined on Erdos-Renyi graphs, expressed as a function of the empirical distributions, we obtain our annealed asymptotic result.Item Large deviation results for critical multitype galton-watson trees(Far East Journal of Mathematical Sciences, 2017) Doku-Amponsah, K.In this paper, we prove a joint large deviation principle in n for the empirical pair measure and empirical offspring measure of critical multitype Galton-Watson trees conditioned to have exactly n vertices in the weak topology. From this result we extend the large deviation principle for the empirical pair measures of Markov chains on simply generated trees to cover offspring laws which are not treated by [10, Theorem 2.1]. For the case where the offspring law of the tree is a geometric distribution with parameter (Formula presented) we get an exact rate function. All our rate functions are expressed in terms of relative entropies. © 2017 Pushpa Publishing House, Allahabad, India.Item Joint large deviation result for empirical measures of the coloured random geometric graphs(SpringerPlus, 2016-07) Doku-Amponsah, K.We prove joint large deviation principle for the empirical pair measure and empirical locality measure of the near intermediate coloured random geometric graph models on n points picked uniformly in a d-dimensional torus of a unit circumference. From this result we obtain large deviation principles for the number of edges per vertex, the degree distribution and the proportion of isolated vertices for the near intermediate random geometric graph models. © 2016, The Author(s).Item Modeling inflation rates and exchange rates in Ghana: application of multivariate GARCH models(2015-02) Nortey, E.N.N.; Ngoh, D.D.; Doku-Amponsah, K.; Ofori-Boateng, K.This paper was aimed at investigating the volatility and conditional relationship among inflation rates, exchange rates and interest rates as well as to construct a model using multivariate GARCH DCC and BEKK models using Ghana data from January 1990 to December 2013. The study revealed that the cumulative depreciation of the cedi to the US dollar from 1990 to 2013 is 7,010.2% and the yearly weighted depreciation of the cedi to the US dollar for the period is 20.4%. There was evidence that, the fact that inflation rate was stable, does not mean that exchange rates and interest rates are expected to be stable. Rather, when the cedi performs well on the forex, inflation rates and interest rates react positively and become stable in the long run. The BEKK model is robust to modelling and forecasting volatility of inflation rates, exchange rates and interest rates. The DCC model is robust to model the conditional and unconditional correlation among inflation rates, exchange rates and interest rates. The BEKK model, which forecasted high exchange rate volatility for the year 2014, is very robust for modelling the exchange rates in Ghana. The mean equation of the DCC model is also robust to forecast inflation rates in Ghana. © 2015, Nortey et al.; licensee Springer.Item Asymptotic Equipartition Properties for simple hierarchical and networked structures(Cambridge University Press, 2011) Doku-Amponsah, K.We prove asymptotic equipartition properties for simple hierarchical structures (modelled as multitype Galton-Watson trees) and networked structures (modelled as randomly coloured random graphs). For example, for large n, a networked data structure consisting of n units connected by an average number of links of order n / log n can be coded by about H × n bits, where H is an explicitly defined entropy. The main technique in our proofs are large deviation principles for suitably defined empirical measures.