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Kayode Adekeye

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Papers by Kayode Adekeye

Course Delivery Evaluation as an Instrument for Quality Enhancement in Higher Education Institutions

Course delivery evaluation of programmes by students in higher education institutions has become ... more Course delivery evaluation of programmes by students in higher education institutions has become a global phenomenon for improving the quality of teaching and learning. From the past, it has been discovered that the quality of effective teaching and learning in Higher Education is dwindling and thus, the relevance of graduates to the development of national growth becomes an issue to be addressed. To solve this challenge, quality control and enhancement of course delivery comes to the fore in attacking the menace. The data used in this chapter consist of six thousand, eight hundred and fifty-eight responses from four hundred and seventy-six courses. The data were clustered first according to departments and then according to the lecturers. The thematic areas studied are lecture delivery, lecturer's attitude to learners, coverage of curriculum, use of library and internet for research, healthy lecturers-learners' relationships, and feedback system. A simple but powerful statistical analysis was deployed to analyse the data. The results reflected areas that have critical effect on teaching and learning. The results showed that 24% of the factors considered in this study have significant effects on effective teaching and learning. Furthermore, about 20% of the lecturers assessed were lacking in the determined factors.

A Topic-Specific Evaluation of Students’ Attitudes Towards Statistics

Bridging the Gap: Empowering and Educating Today’s Learners in Statistics. Proceedings of the Eleventh International Conference on Teaching Statistics, Dec 1, 2022

This study involves an evaluation of students' attitudes towards various topics in statistics. Th... more This study involves an evaluation of students' attitudes towards various topics in statistics. The purpose of the study is to determine how students' attitudes towards statistics vary across different topics and to determine possible changes in students' attitudes from the beginning to the end of a course. The target population is that of students taking a statistics course for non-majors at a university in Nigeria. The study involved a pre-test (within the first week of the course) and a post-test (applied at the end of the course) focused on specific topics in the statistics course. Results indicated that students' attitudes were moderately positive at the onset and remained the same at the end of the course for most topics. Implications for teaching statistics are discussed.

Thermal analysis for a gravity-driven liquid film along an inclined porous substrate

Journal of the Taiwan Institute of Chemical Engineers, 2021

Abstract This paper investigates the entropy generation in a thin film fluid flow along a heated ... more Abstract This paper investigates the entropy generation in a thin film fluid flow along a heated inclined substrate. The free end of the thin film is assumed to be exposed to adiabatic condition. The mathematical formulation for the fluid and heat flow leads to a dimensionless Boundary Value Problem (BVP) together with a partial differential equation (PDE). The exact solution of the BVP problem was obtained and the analytical solution for the PDE was obtained with the use of separation of variables. These solutions were used to profile the entropy generation in the thin film flow. The result earlier obtained in the absence of porous permeability was validated as a special case of the work and our contributions to knowledge were highlighted in the porous substrate case.

Process Capability Indices Based on Median Absolute Deviation

Process capability is the performance of a process under normal and in-control conditions. Its in... more Process capability is the performance of a process under normal and in-control conditions. Its indices are to measure the inherent variability of a process and thus to reflect its performance. To calculate the capability indices for key characteristics, most industries normally assume that the distribution of their process output is normal. However, in practice, most key quality characteristics do fails the normality test and thus the accuracy of normal based process capability indices becomes doubtful and hence they cannot really reflect the performance of a process. This paper proposes the determination of the common process capability indices based on the median absolute deviation. The median absolute deviation is a robust estimate of variability when the sample data are non- normal or are skewed. Real process data and simulated process data from heavily skewed distributions are presented to demonstrate the application of the proposed indices and the results were compared with th...

A Review of Change Point Estimation Methods for Process Monitoring

Applied and Computational Mathematics, 2021

Evaluating Process Capability Indices of a Manufacturing Process 107 2 Process Capability Indices

The effectiveness of a manufacturing product produced depends on whether the specified standards ... more The effectiveness of a manufacturing product produced depends on whether the specified standards by the management / production engineers are met or not. It is possible that a process will be stable but will not meet the specification set by the production engineer or management. In order to determine whether a process meets the specification of the process engineer or management, process capability indices (PCIs) are often used. This study is aimed at evaluating the capability and the percentage of nonconforming unit of a manufacturing process. Data on two quality characteristics were extracted from the records of Evans Medical PLC, Agbara, Nigeria. The process capability indices were used to determine the capability of the process and the percent non-conforming was used to check the amount of the process that does not meet the required standard. The obtained results reflect the amount of the products produced during the period of study that do not conform to specification and the ...

Experimental design for quality improvement in the presence of time-trends

This thesis concentrates on an aspect of experimental design for quality improvement. It is often... more This thesis concentrates on an aspect of experimental design for quality improvement. It is often observed that there is a time trend that influences the experimental data for a given design. For instance, this might be due to a machine part that deteriorates during experimentation. This always leads to data with different distribution under the same experimental setting when observed at a later period of time. In this dissertation we want to deal with the problems of time trends for a given process. The theoretical and practical aspects of such time trends were taken into consideration. In the theoretical aspect we try to improve methods to get rid of time trends influence by determination of trend resistance using factorial design. Systematic run order in which the estimates for factorial effects of interest are time trends resistant are considered. Here, time trends are modelled as linear and quadratic functions. Several approaches for constructing systematic run order of two lev...

Comparison of Capability Analysis of Cumulative Cardiac Thoracic Ratio (CTR) Outputs

This study investigated the Capability Process Analysis of cumulative Cardiac Thoracic Ratio (CTR... more This study investigated the Capability Process Analysis of cumulative Cardiac Thoracic Ratio (CTR) during Radiological Chest Examination using MX.4 Radiological Diagnostic Machine (DRM) at the Fate Medical Foundation Radiological Department, Auchi. The data for the study are classified as raw and simulated CTR values. Statistical process control was investigated to address process stability and capability analysis was performed for the two processes. The pattern of the means of the raw and simulated values was investigated using normal probability plots and empirical CDF functions. The raw computed CTR values and simulated CTR values confirmed that the system is operating under 1.0 – 1.3 sigma level for the raw CTR values. Around 28-39% of the raw CTR values obtained fall outside the specification limits. In addition, for all the cumulative raw CTR values suggested that the process is off centered and is towards the lower specification limit. Further study should be conducted on lar...

On Performance of Two-Parameter Gompertz-Based X¯ Control Charts

Journal of Probability and Statistics, 2020

In this paper, two methods of control chart were proposed to monitor the process based on the two... more In this paper, two methods of control chart were proposed to monitor the process based on the two-parameter Gompertz distribution. The proposed methods are the Gompertz Shewhart approach and Gompertz skewness correction method. A simulation study was conducted to compare the performance of the proposed chart with that of the skewness correction approach for various sample sizes. Furthermore, real-life data on thickness of paint on refrigerators which are nonnormal data that have attributes of a Gompertz distribution were used to illustrate the proposed control chart. The coverage probability (CP), control limit interval (CLI), and average run length (ARL) were used to measure the performance of the two methods. It was found that the Gompertz exact method where the control limits are calculated through the percentiles of the underline distribution has the highest coverage probability, while the Gompertz Shewhart approach and Gompertz skewness correction method have the least CLI and ...

Mathematical Analysis of a Reactive Viscous Flow through a Channel Filled with a Porous Medium

Journal of Mathematics, 2016

An investigation has been carried out to study entropy generation in a viscous, incompressible, a... more An investigation has been carried out to study entropy generation in a viscous, incompressible, and reactive fluid flowing steadily through a channel with porous materials. Approximate solutions for both velocity and temperature fields are obtained by using a rapidly convergent Adomian decomposition method (ADM). These solutions are then used to determine the heat irreversibility and Bejan number of the problem. Variations of other important fluid parameters are conducted, presented graphically, and discussed.

Evaluation of global and local indicator of spatial autocorrelations of kenaf EVALUATION OF GLOBAL AND LOCAL INDICATOR OF SPATIAL AUTOCORRELATIONS OF KENAF IN EXPERIMENTAL PLOTS IN SOUTH WESTERN NIGERIA

A study was conducted to assess spatial variations in experimental plots through the global and l... more A study was conducted to assess spatial variations in experimental plots through the global and local indicator of spatial autocorrelation of kenaf. Field data obtained from experiment conducted at both Ilora and Ikenne outstations of the Institute of Agricultural Research and Training, Ibadan, Nigeria in 2006 were used to investigate spatial variability in experimental plots. The descriptive statistics showed that sample mean (μ) from different tessellated plots of the experimental sites were biased estimators which might have been probably caused by spatial variations in the experimental sites. Also, the global Moran I and Moran I scatter plots showed that these can be used as a measure of variation between the plots. Generally, the selected spatial autocorrelation indicators were found to be consistent with some other spatial statistical analytical tools.

Performance evaluation of some improved control charts for proportion of non-conforming units

The proportion (p) chart is widely used to monitor the fraction of non-conforming units in order ... more The proportion (p) chart is widely used to monitor the fraction of non-conforming units in order to detect whether the quality of a process improves or deteriorates. Different alternatives to the p chart have been suggested by various authors. In this paper, three of the alternative charts are considered. These are the T. P. Ryan modified limits [Statistical methods for quality improvement. 2 nd ed., NY: Wiley (2000; Zbl 0941.62129)], G. Chen limits [J. Qual. Technol. 30, No. 2, 142–151 (1998)] and D. B. Laney limits [Qual. Eng. 14, No. 4, 531–537 (2002)]. The performance of these improved control charts for proportion of nonconforming units is evaluated using the average run length and the probability of false alarm. The proportion of nonconforming units of a process is used to evaluate the performance of the three considered improved p control charts. The obtained results shows that all the three charts are better than the traditional p chart with the Ryan approach been discovered...

Bootstrap-T Technique for Minimax Multivariate Control Chart

Open Journal of Statistics, 2012

Bootstrap methods are considered in the application of statistical process control because they c... more Bootstrap methods are considered in the application of statistical process control because they can deal with unknown distributions and are easy to calculate using a personal computer. In this study we propose the use of bootstrap-t multivariate control technique on the minimax control chart. The technique takes care of correlated variables as well as the requirement of the distributional assumptions needed for the operation of the minimax control chart. The bootstrap-t technique provides the mean ˆB  of all the bootstrap estimators  is the estimate using the bootstrap sample and B is the number of bootstraps. The computation of the proposed bootstrap-t minimax statistic was performed on the values obtained from the bootstrap estimation. This method was used to determine the position of the four control limits of the minimax control chart. The bootstrap-t approach introduced to minimax multivariate control chart helps to detect shifts in the mean vector of a multivariate process and it overcomes the computational complexity of obtaining the distribution of multivariate data.

Design of Cusum Scheme for Monitoring Road Accident Fatalities

Open Journal of Statistics, 2012

In recent years, road accident fatalities in Nigeria have continued to be on the increase. Thus, ... more In recent years, road accident fatalities in Nigeria have continued to be on the increase. Thus, urgent attention is needed to reduce or eliminate road accidents fatalities. To achieve this goal, the cumulative sum (Cusum) control chart scheme was designed for monitoring the road accident fatalities using the recorded occurrence of road accident fatalities in a state in the western part of Nigeria. The designed Cusum detects the period of the years when the highest occurrence of road accident fatalities occurred. These periods were observed to be festive periods such as Christmas, Easter, Eid-el-Kabir, and Eid-el-Moluod. Therefore, the festive periods of the year should be used as benchmark by road managers as periods where more attention or precaution measure should be put in place on the roads to drastically reduce or eliminate high occurrence of road accident fatalities. The designed Cusum control chart can be adapted for other states in the country and also for the larger society for detecting the periods when the rate of death as a result of road accidents was prevalent.

Minimax Multivariate Control Chart Using a Polynomial Function

Applied Mathematics, 2011

Minimax control chart uses the joint probability distribution of the maximum and minimum standard... more Minimax control chart uses the joint probability distribution of the maximum and minimum standardized sample means to obtain the control limits for monitoring purpose. However, the derivation of the joint probability distribution needed to obtain the minimax control limits is complex. In this paper the multivariate normal distribution is integrated numerically using Simpson's one third rule to obtain a non-linear polynomial (NLP) function. This NLP function is then substituted and solved numerically using Newton Raphson method to obtain the control limits for the minimax control chart. The approach helps to overcome the problem of obtaining the joint probability distribution needed for estimating the control limits of both the maximum and the minimum statistic for monitoring multivariate process.

On the Comparison of Run Orders of Unreplicated 2 k–p Designs in the Presence of a Time Trend

Metrika, 2006

The response from a factorial experiment carried out in a time sequence may be affected by uncont... more The response from a factorial experiment carried out in a time sequence may be affected by uncontrollable variables that are highly correlated with the time in which they occur. In such a situation, one possibility is to randomize the run order of the experiment. Another possibility is to use a systematic run order that is robust against time-trends. Since randomized run orders make the time trend part of the error, it can be hoped that systematic run orders will be more effective to identify truly active factors. In this paper, a simulation study is used to compare the performances of the randomized and the systematic run orders. The response from an experiment where we have observed a strong time-trend is used to demonstrate the influence of a realistic time trend on the run orders under consideration. The performance of the run orders is then measured by taking the probabilities of false rejection and the probabilities of detection of active contrasts. Our results show that the randomized run order managed to keep the nominal level, while the systematic did not. Additionally, when there were active factors, then the systematic run orders did not achieve more power than did the randomized run order.

Derivation of the Limits for Control Chart Using the Median Absolute Deviation for Monitoring Non-Normal Process

Journal of Mathematics and Statistics, 2012

The Shewhart and S control charts, in the literature, were combined to evaluate the stability of ... more The Shewhart and S control charts, in the literature, were combined to evaluate the stability of a process. These charts were based on the fundamental assumption of normality of the quality characteristics under investigation. Approach: In practice, the normality assumption was often violated by real life data, therefore, use of the Shewhart and S control charts on real life data might leads to misplacement of control limits. There were many alternatives in the literature to handle non-normality of quality characteristics. The Median Absolute Deviation (MAD) claimed in the literature to be the best estimate when the data under consideration is non-normal. Thus in this study, we derived the control limits for the-control chart using the median absolute deviation for monitoring process stability when the quality characteristic under investigation was non-normal. The derived control limits were compared with the control limits when the sample standard deviation was used as a measure of controlling the process variability using manufacturing process (real life) data. Furthermore, a simulation study was carried out to evaluate the performance of the proposed MAD based control charts on both normal and non-normal process. Conclusion: The obtained results show that the derived control limit is an improvement on the control limit of the Shewhart and that the MAD control charts performed better for non-normal process than for normal process.

On logistic regression versus support vectors machine using vaccination dataset

Journal of the Nigerian Society of Physical Sciences, Mar 6, 2024

The performance of two classification techniques, logistic regression and Support Vector Machines... more The performance of two classification techniques, logistic regression and Support Vector Machines (SVMs), in assessing vaccination data is investigated in this study. The model was trained based on leave-out-one cross validation to obtain an accurate result. Simulated with ten thousand replications, a life data set was used to establish a better model. The findings from the simulation revealed that the logistic regression model slightly outperformed the SVM while the life data shows that the tuned SVM outperformed both the logistic and the SVM. This demonstrates the practical utility of advanced approaches such as SVMs in difficult categorization scenarios such as vaccination prediction. The study emphasizes the superiority of the customized SVM model in this setting, as well as the potential of machine learning approaches to increase comprehension of complicated healthcare scenarios and guide data-driven decision-making for influencing vaccination plans and public health. The study recommends the use of logistic regression if the data point is high.

Modeling the Response Rate of Apache Web Server Using Extreme Value Theory

Regularized Models for Fitting Zero-Inflated and Zero-Truncated Count Data: A Comparative Analysis

Mathematical Modelling of Engineering Problems

Generalized Linear Models (GLMs) are widely recognized for their efficacy in fitting count data, ... more Generalized Linear Models (GLMs) are widely recognized for their efficacy in fitting count data, superior to the Ordinary Least Squares (OLS) approach. The incapability of OLS to suitably handle count data can be attributed to its tendency to overfit. This study proposes the utilization of regularized models, specifically Ridge Regression and the Least Absolute Shrinkage and Selection Operator (LASSO), for fitting count data. These models are compared to frequentist and Bayesian models commonly used for count data fitting, such as the Dirichlet prior mixture of generalized linear mixed models and the discrete Weibull. The findings reveal Ridge Regression's superiority over all other models based on the Akaike Information Criterion (AIC). However, its performance diminishes when evaluated using the Bayesian Information Criterion (BIC), even though it still outperforms LASSO. The study thereby suggests the use of regularized regression models for fitting zero-inflated count data, as demonstrated with simulated data. Further, the appropriateness of regularized zero for zero-truncated count is exemplified using life data.