Zakiyah Zain

Zakiyah Zain
Universiti Utara Malaysia | UUM · School of Quantitative Sciences

PhD Statistics

About

75
Publications
17,327
Reads
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317
Citations
Introduction
Equipped with 13 years of industrial experience in process and quality engineering, my mission is to impart some knowledge and skills in teaching/learning statistics. Interests include quality control, acceptance sampling, survival analysis, lean six sigma, cancer, public health, and statistics education. Prior experience in conducting quality system audits, training/consultation on problem-solving (QC) techniques, and developing/testing/implementing cross-site issues management system.

Publications

Publications (75)
Article
Full-text available
Honesty, transparency, and responsibility to the organisation depicts the integrity personality of an officer towards the organisation. Therefore, integrity is one of the components that could drive the development of the organisation to be more progressive and excellent in its specialisation. Various data could be assessed by the management to eva...
Article
Full-text available
In this paper, a new group chain sampling plan (NGChSP) for a truncated life-test is established when product lifetime follows Marshall-Olkin extended Lomax (MOEL) distribution. The minimum number of groups, , and the operating characteristic value are calculated by satisfying the specified consumer's risk, the test termination time, and the mean r...
Article
Full-text available
This paper is the first to introduce Marshall Olkin extended Lomax (MOEL) distribution in a two-sided group chain acceptance sampling plan (TSGChSP). The plan's benefit is that it allows multiple product inspections concurrently. For constructing the plan, the methodology is based on the following six phases: (i) identifying design parameters, (ii)...
Article
Full-text available
Acceptance sampling is a statistical quality control technique that consists of procedures for sentencing one or more incoming lots of finished products. Acceptance or rejection is based on the inspection of sampled products drawn randomly from the lot. The theory of previous acceptance sampling was built upon the assumption that the process from w...
Article
Full-text available
Acceptance sampling is a well-established statistical technique in quality assurance. Acceptance sampling is used to decide, acceptance or rejection of a lot based on the inspection of its random sample. Experts concur that the Bayesian approach is the best approach to make a correct decision, when historical knowledge is available. This paper sugg...
Article
Full-text available
Acceptance sampling is an important technique in quality assurance; its main goal is to achieve the most accurate decision in accepting lot using minimum resources. In practice, this often translates into minimizing the required sample sizes for the inspection, while satisfying the maximum allowable risks by consumer and producer. Numerous sampling...
Article
Full-text available
Acceptance sampling remains as a popular method of quality assurance in many industries. The primary goal is to reach an accurate decision whether to accept or reject a lot based on the results from sample inspection at a minimal cost. In this study, a new two-sided group chain acceptance sampling plan (NTSGChSP) using the Marshall-Olkin Extended E...
Article
Full-text available
This study constructs new two-sided group chain acceptance sampling plans (NTSGChSP-1) for generalized exponential distribution using minimum angle method. The minimum angle method is slightly advantageous over the previous methods of minimizing consumer’s and procedure’s risk, as it considers the optimal number of groups, g associated with the sma...
Article
The established group chain acceptance sampling plans (GChSP-1) functions with five acceptance criteria, while the modified group of chain acceptance sampling plans (MGChSP-1) operates with three acceptance criteria. Since the acceptance criteria affect the performances of the sampling plans, therefore, this article suggests a balanced approach by...
Article
Purpose This paper introduces group chain acceptance sampling plans (GChSP) for a truncated life test at preassumed time by using the minimum angle method. The proposed method is an approach, where both risks associated with acceptance sampling, namely consumers’ and producer’s risks, are considered. Currently, the GChSP only considers the consumer...
Article
Full-text available
Control chart is as a highly reputable statistical quality control tool in monitoring process stability. The classical control charts are designed on the basis of normality assumption, which is often not valid for real situations in industry; such violation of normality render the charts less accurate. This paper presents an alternative skewness co...
Article
Full-text available
Control chart has been long-established among the highly reputable tools in statistical process control (SPC) with extensive industrial application. Shewhart chart is one of the most popular charts, but its reliability is arguable when dealing with skewed data, due to inflated false alarm rate (Type I error). In alleviating the problem, this study...
Article
Full-text available
The performance of a sampling plan from group sampling family is measured by its minimum number of groups and probability of lot acceptance. Basically, once the minimum number of groups is determined, the corresponding probability of acceptance can be obtained for various sets of design parameters. This article compares the performance of two accep...
Conference Paper
Dengue is growing most rapidly in tropical and subtropical countries where majority of the world’s population reside and increasing health and economic burden. It has become endemic in Malaysia since 1971 and reported cases have increased in over 6-fold over the past decade. This paper demonstrates how survival analysis techniques are used to compa...
Conference Paper
Acceptance sampling is a fundamental statistical quality control procedure widely used in industries to decide whether to accept or to reject a product lot. Currently, the development of acceptance sampling plans focuses on the group chain acceptance sampling plans (GChSP) since the plans have many advantages compared to the established plans. Howe...
Conference Paper
In this study, survival analysis is employed to determine the trends of profile analysis and evaluate the survival rate of bankruptcies in Malaysia from years 2005 to 2015. Recent report states a total of 94,408 people involved in bankruptcy cases from year 2013 until August 2017; about 97% of these bankruptcies are caused by inability to repay ins...
Article
The established modified group chain acceptance sampling plans (MGChSP) only considered the consumer’s risk when developing the plans and turned down the producer’s risk, which means the established MGChSP satisfied the consumer but not the producer. Based on the above problem, this article proposes the minimum angle method for the MGChSP as the me...
Book
As Leonardo da Vinci once said, Simplicity is the ultimate sophistication. This book is evidence of how diverse problems can be solved using basic statistical methods; from the minute molecule level to widespread epidemic issues, data analysis can be accomplished using basic statistical methods with sound scientific thinking.This book is a valuable...
Conference Paper
Acceptance sampling is a statistical quality control technique whereby the final decision to accept or reject a lot is based on the outcome from the inspection of its sample. A recent development in acceptance sampling includes the group chain acceptance sampling plan (GChSP) to rectify the problems with the single acceptance sampling plans (SSP) a...
Article
There are several methods used such as minimizing the consumer’s risk and minimum angle method (minimizing consumer’s and producer’s risks simultaneously) when developing a new acceptance sampling plan. For the minimizing consumer’s risk method, researchers have conducted a thorough research and all the findings using this method are well-discussed...
Article
This article develops group chain acceptance sampling plans (GChSP) for Gamma distribution when the life test is trun-cated at a pre-specified time. The Gamma distribution is chosen as most electronic products such as carbon-film resistors, light-emitting diodes and integrated logic family follow this distribu-tion. The design parameters such as th...
Chapter
This chapter investigates the group chain sampling plan where it is a combination of chain sampling plan and group sampling plan. The group chain sampling plan is shown to be a better sampling plan compared to the group sampling plan with c=0 and c=1. The advantages of group chain sampling plan are also highlighted.
Article
Full-text available
Colorectal cancer, which is also known as bowel cancer, colon cancer, or rectal cancer, is the third most common cancer worldwide, and the second most common in Malaysia. In most situations, the tumor/cancer may return even after the tumor removal. The impact of the type of surgery performed for tumor removal on the occurrence of a new tumor and th...
Article
This paper develops group chain sampling plans (GChSP) for Exponential distribution when the life test is truncated at a pre-assumed time. The performances of the GChSP such as the number of minimum groups, g and probability of lot acceptance, L(p) are calculated by satisfying the consumers risk, β at a certain specified design parameter. Quality p...
Conference Paper
Full-text available
Control chart is established as one of the most powerful tools in Statistical Process Control (SPC) and is widely used in industries. The conventional control charts rely on normality assumption, which is not always the case for industrial data. This paper proposes a new S control chart for monitoring process dispersion using skewness correction me...
Conference Paper
Acceptance sampling is used in industry to ensure the quality of the product which is satisfied by both consumer and producer. In this paper, modified group chain sampling plan is developed for a truncated life test when the lifetime of an item follows exponential distribution. Optimal number of groups and probability of lot acceptance are determin...
Conference Paper
This paper aims to measure the performance of university food service based on students’ perception. Two cafeterias were chosen for comparison: one located at student residential hall (Café 1) and another at the university administration centre (Café 2). By considering the components of importance and satisfaction, the Heterogeneous Customer Satisf...
Article
Multiple event times or endpoints often arise in survival data and this complicates analysis especially when all endpoints are of equal interest. However, to conclude on the overall treatment advantage of a new drug, a single statistic is required. The cumulative treatment advantage is often measured by the score statistic for each endpoint. This s...
Article
Full-text available
Acceptance sampling is a quality control technique widely used by companies in deciding whether or not to accept a lot or batch of products based on the inspection result of a sample taken from the lot. Majority of acceptance sampling plans are developed assuming symmetrical data distribution, whereas actual scenarios include product lifetime which...
Article
Full-text available
This research examined the usage of the parametric method in comparing two or more means as independent group test, for instance, the Alexander-Govern (AG) test. The utilization of mean as the determinant for the center of distribution of variance diversity takes place in testing, and the test provides excellence in maintaining the amount of Type I...
Article
In this study, group acceptance sampling plan (GASP) proposed by Aslam et al. (2011) is redesigned where the lifetime of test items are following Pareto distribution of 2nd kind. The optimal plan parameters are found by considering various pre-determined designed parameters. The plan parameters were obtained using the optimization solution and it a...
Conference Paper
Group chain sampling plans are developed based on truncated life test when lifetime of a product follows some selected lifetime distributions. These distributions are Rayleigh distribution, Log-Logistic distribution, Inverse Rayleigh distribution, Gamma distribution and Exponential distribution. The design parameters such as the number of optimal g...
Article
This paper introduces group chain sampling plans for Inverse Rayleigh distribution when the life test is truncated at a pre-assumed time. The design parameters such as the number of optimal groups and operating characteristic values are calculated by satisfying the consumer’s and producer’s risks at a certain specified quality level. Quality level...
Conference Paper
Full-text available
This article proposes new EWMA chart in observing process standard deviation or dispersion with sample range of Weibull data using weighted variance method (WV). This control chart, called Weighted Variance EWMA sample range WV-EWMASR chart hereafter. The proposed WV-EWMASR chart compared with standard EWMASR of [7], skewness correction R chart (SC...
Article
Full-text available
This paper proposes a new S control chart for monitoring process dispersion of skewed populations. This control chart, called Scaled Weighted Variance S control chart (SWV-S) hereafter, this new SWV-S control chart is an improvement of the Weighted Variance S control chart (WV-S) proposed by Khoo et al. [11]. The proposed control chart reduces to t...
Article
Full-text available
This research dealt with making comparison of the independent group tests with the use of parametric technique. This test used mean as its central tendency measure. It was a better alternative to the ANOVA, the Welch test and the James test, because it gave a good control of Type I error rates and high power with ease in its calculation, for varian...
Article
This paper introduces group chain sampling plans for Log-Logistic distribution when the life test is truncated at a pre-assumed time. The design parameters such as the number of optimal groups and the operating characteristic values are calculated by satisfying the consumer’s and producer’s risks at a certain specified quality level. Quality level...
Conference Paper
Procrastination is the action of delaying or postponing something such as making a decision or starting or completing some tasks or activities. According to previous studies, students who have a strong tendency to procrastinate get low scores in their tests, resulting in poorer academic performance compared to those who do not procrastinate. This s...
Article
This paper introduces group chain sampling plan for Rayleigh distribution when the life test is truncated at a pre-assumed time. The design parameters such as the number of optimal groups and the operating characteristic values are calculated by satisfying the consumer’s and producer’s risks at a certain specified quality levels. Quality levels are...
Article
Full-text available
Aims and Objectives: To evaluate the efficiency and reliability of the Alexander-Govern (AG) test and the Winsorized Modified One Step M-estimator in the Alexander-Govern (AGWMOM) test, using real life data. Methods: Test of homogeneity of variance was done from real life data, comprising of young, middle and old groups, using the Levene's test to...
Article
In this paper, modified group chain sampling plan is developed for a truncated life test when the lifetime of an item follows Rayleigh distribution. Optimal number of groups and operating characteristic value are obtained by obeying the specified consumer’s risk, test termination time and mean ratio.
Conference Paper
In clinical trials, the main purpose is often to compare efficacy between experimental and control treatments. Treatment comparisons often involve multiple endpoints, and this situation further complicates the analysis of survival data. In the case of tumor patients, endpoints concerning survival times include: times from tumor removal until the fi...
Conference Paper
In this article, we proposed an acceptance sampling plan based on generalized group chain truncated life test. The decision on acceptance of a submitted lot can be made by using the cumulative information of the immediately preceding samples. The design parameters of the proposed plan such as the minimum number of groups are found to satisfy the de...
Conference Paper
This paper outlines the framework for application of lean six sigma (LSS) methodology to improve semiconductor assembly cycle time in a make-to-order (MTO) business environment. The cycle time reduction is the prime objective in the context of an overall productivity improvement particularly in the MTO environment. The interaction of the production...
Article
Full-text available
This study centres on the comparison of independent group tests in terms of power, by using parametric method, such as the Alexander-Govern test. The Alexander-Govern (AG) test uses mean as its central tendency measure. It is a better alternative compared to the Welch test, the James test and the ANOVA, because it produces high power and gives good...
Article
Full-text available
This study examines the use of independent group test of comparing two or more means by using parametric method, such as the Alexander-Govern (AG) test. The Alexander-Govern test is used for comparing two or more groups and is a better alternative compared to the James test, the Welch test and the ANOVA. This test has a good control of Type I error...
Article
Full-text available
This research centres on independent group test of comparing two or more means by using the parametric method, namely the Alexander-Govern test. The Alexander-Govern (AG) test uses mean as a measure of its central tendency. It is a better alternative to the Welch test, James test and the ANOVA, because it has a good control of Type I error rates an...
Article
Full-text available
The main purpose of this study is to intend a generalized chain sampling plan for Pareto distribution of the 2 nd kind. The designed parameters such as the minimum sample size and operating characteristic values are found by satisfying the consumer's risk at the specified quality levels in terms of average. The results are explained by an example.
Article
This paper proposes plan that improve on existing group chain and modified group chain sampling plans. The plan is mixed in the sense that they combine elements from both preceding and succeeding lot information’s. This combination gives a higher probability of lot acceptance and better operating characteristic curve. The design parameters such as...
Article
Disability may involve visual disability, physical disability, learning disorder, speech disorder, mental disorder and others various disabilities. This situation can reduce the quality of life, and causes clear drawback to that person. Due to this, in many countries, there are scholarships for students with disability, and students with disability...
Article
Full-text available
In this study, a Group Acceptance Sampling Plan (GASP) for lot resubmitting is developed for situations in which the lifetime of a product follows the generalized Pareto distribution. The design parameters such as minimum group size and acceptance number are observed when the consumer's risk, number of testers and the test termination time are pre-...
Article
Full-text available
The main goal of this study is to propose a chain Group Acceptance Sampling Plan (GASP) when the life time of a product follows the Pareto distribution of the 2nd kind. The design parameters such as the minimum group size and operating characteristic values are obtained by satisfying the producer's and consumer's risks at the specified quality leve...
Article
In this paper group acceptance sampling plan for truncated life test are developed using two-sided chain sampling method, when the life time of the product follows Pareto distribution of the 2nd kind. The design parameters of the proposed plan are determined for pre-specified acceptance number by satisfying the producers and consumers risks at the...
Article
This research study elaborate an economic reliability group acceptance sampling plan using the Poisson and Weighted Poisson distributions when the lifetime of the product follows the Pareto distribution of 2nd kind. The tables and examples of this research analysis provides the minimum termination time necessary to assure a certain mean or average...
Article
Full-text available
Colorectal cancer is the third and the second most common cancer worldwide in men and women respectively, and the second in Malaysia for both genders. Surgery, chemotherapy and radiotherapy are among the options available for treatment of patients with colorectal cancer. In clinical trials, the main purpose is often to compare efficacy between expe...
Article
Purpose We wanted to confirm the benefit of mometasone furoate (MF) in preventing acute radiation reactions, as shown in a previous study (Boström et al, Radiother Oncol 2001;59:257-265). Methods and Materials The study was a double-blind comparison of MF with D (Diprobase), administered daily from the start of radiation therapy for 5 weeks in pat...
Article
Progression-free survival (PFS), time-to-progression (TTP) and overall survival (OS) are examples of multiple endpoints commonly used in clinical trials of cancer patients. PFS is increasingly used as a primary endpoint in evaluation of patients with solid tumors, while multiple endpoints are often analysed independently. These endpoints are indeed...
Article
Full-text available
Multiple endpoints are common in survival data and this scenario complicates the analysis. For example, sets of responses concerned with survival times in a single clinical trial include: time to first cardiac event and time to death from any cause; time to loss of vision in the left eye and time to loss of vision in the right eye; and times from e...

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