The performance of robust-diagnostic F in the identification of multiple high leverage points

High leverage points have undue effects on the Least Square estimates. They are responsible for misleading conclusions in regression and multicollinearity problems. Hence, it is imperative to detect high leverage points and use robust estimators to estimate the parameters of a regression model, so as to arrive at valid conclusions. Several well-known methods have failed to detect multiple high leverage points correctly because of the swamping and/or masking effects. The Diagnostic Robust Generalized Potential (DRGP), is an appealing alternative method that successfully detects high leverage points correctly. However, for small percentages of high leverage points, it has the tendency to identify few low leverage points to be points of high leverage. In this paper, an attempt is made to correctly identify real high leverage point by reducing swamping effects. We propose a method we call Robust Diagnostic-F (RDF), in which robust approach is employed to detect the suspected high leverage points. Then, F statistics that relates the change in data covariance structure is used to confirm the suspicion. The performance of RDF is evaluated through real data and simulations. Comparisons are also made with existing methods

An exploration of experts' views on the integration of vertical greenery as public art in Malaysian cities

Vertical greenery (VG) is plants that can be grown on, up, or against internal or external walls of buildings or as freestanding structures. An urban area is in need of more greenery in its surroundings and one method is by increasing the implementation of VG in urban areas. This is due to various benefits gained by implementing VG in terms of the aesthetic, economic and environment aspect. Furthermore, to sustain its usage, VG must be explored creatively. Public art (PA) is a structure or a form that contains an artistic expression that is located in a freely accessible city’s public space. Sadly, PA in Malaysia is often used merely to decorate and fill-up the public spaces. This scenario is actually contradicting with the ultimate objective of PA, which is it should serve as an artistic expression that can be used, appreciated and has benefits to the public. Hence, there is a need to improve the selection and appearance of PA in Malaysian cities. With this premise, this research sets out to explore the potentials of VG to be integrated as a PA in the city’s public space. This research is a part of author’s Master Degree thesis titled “Analyzing the Potentials of Vertical Greenery in Malaysian Urban Context”. The aim of this paper is to discover the perspectives of experts in landscape architecture and PA field on the potentials of the integration. This is because, a majority of research in VG, especially in Malaysia focuses on environmental and technical aspects of VG, rather than looking at creative methods to approach VG. This paper presents two research objectives; (i) to identify the potentials of its integration from experts in the field of landscape architecture and PA and, (ii) to study the attributes of VG as a PA from their perspectives. Semistructured interviews were conducted with two experts in VG and two experts in PA. Findings suggest that there are five potentials for VG as a PA: to use the abundant Malaysian natural resources, to be a leader in VG for South East Asia (SEA) region, to support the nation’s green aspiration, sustainability perspectives and to have an artistic green wall. Meanwhile, there are 17 attributes of VG as PA listed by the experts; (a) large size and scale, (b) fair percentage of greenery, (c) proper maintenance, (d) uncommon geometric patterns, (e) using unconventional materials, (f) creative implementation method, (g) direct art intervention, (h) surprise elements, (i), out of the norm design, (j) wonder about the creative works, (k) the VG needs to have some meaning behind it, (l) combine material of living and non-living things, (m) creative utilisation of plants, (n) use recycled material, (o) continuing with the surroundings, (p) interaction with public, (q) visibly seen by the public and (r) impactful. Thus, the findings imply that all experts were in agreement and believe that VG has high potential to be integrated as a PA. Finally, the findings also reveal several measures to improve the selection and appearance of PA as VG in the Malaysian cities

APPROACHING VERTICAL GREENERY AS PUBLIC ART: A REVIEW ON POTENTIALS IN URBAN MALAYSIA

When landscape becomes the work of art, it is becoming more significant to the community. However, finding practical and effective ways in which public art could present an environmental cause is yet to be fully explored. Therefore, one way to approach this issue is by increasing the Vertical Greenery technology's application, especially at the wall of building in the city. Vertical Greenery (VG) varies in term of definition, but all in all, it can be interpreted as the growing of plants in, up, or against the facade of a building. On the other hand, public art can be referred as an artwork that is located in public space, which welcomes public interactions. Thus, in order to further study the potential of VG implementation as public art, this paper reviews 25 selected real life projects in urban Malaysia as reference studies, which include Kuala Lumpur, Selangor Johor and Penang that applied VG in their development. It explored whether the VG’s implemented is, for public art. Based on the study, the researcher found that VG is implemented for its environmental, economic and aesthetic value. The researcher also noted that all VG that has been implemented at the developments in some ways portray the basic idea of public art which is an artistic expression that is positioned in a freely accessed public space for the public to use, but not just any art placed outside yet still carries the basic concept of art, which to beautify spaces. Hence, the result had shown significant potentials for VG to be introduced as a new form of sustainable public art in urban Malaysia

Approaching vertical greenery as public art: a review on potentials in urban Malaysia

When landscape becomes the work of art, it is becoming more significant to the community. However, finding practical and effective ways in which public art could present an environmental cause is yet to be fully explored. Therefore, one way to approach this issue is by increasing the Vertical Greenery technology's application, especially at the wall of building in the city. Vertical Greenery (VG) varies in term of definition, but all in all, it can be interpreted as the growing of plants in, up, or against the facade of a building. On the other hand, public art can be referred as an artwork that is located in public space, which welcomes public interactions. Thus, in order to further study the potential of VG implementation as public art, this paper reviews 25 selected real life projects in urban Malaysia as reference studies, which include Kuala Lumpur, Selangor Johor and Penang that applied VG in their development. It explored whether the VG’s implemented is, for public art. Based on the study, the researcher found that VG is implemented for its environmental, economic and aesthetic value. The researcher also noted that all VG that has been implemented at the developments in some ways portray the basic idea of public art which is an artistic expression that is positioned in a freely accessed public space for the public to use, but not just any art placed outside yet still carries the basic concept of art, which to beautify spaces. Hence, the result had shown significant potentials for VG to be introduced as a new form of sustainable public art in urban Malaysia

Evaluating efficiency of Islamic banks using data envelopment analysis: international evidence

This study investigates the efficiency of Islamic banks in four regions; Africa, the Far East and Central Asia, Europe and the Middle East during the period of 2003-2008. The non-parametric approach, Data Envelopment Analysis is utilised to analyse the technical and scale efficiencies of Islamic banks. Overall, the results suggest that mean efficiency of Islamic banks have declined over the period from 0.746 in 2003 to 0.544 in 2008. During the period of study, our results suggest that pure technical inefficiency has largely resulted in the overall inefficiency of Islamic banks. Using a series of parametric and non-parametric tests, our results indicate that there are significant differences in efficiencies between size and not between regions. Large sized banks tend to be efficient than the small and medium sized banks

Appreciation of vertical greenery in a city as public art

Vertical greenery (VG) is greenery where plants can be grown on, up, or against internal or external walls of buildings or as freestanding structures. Whereas, public art (PA) is a structure or form that contains an artistic expression. It is placed in public spaces. VG has gained tremendous popularity in recent years, and this offers an opportunity to integrate it as a part of public art in cities. A place with a combination of art and aesthetics with environmental principles would become a new urban art that will help extend VG’s survivability and human security in the future. Most research in VG focuses on an environmental and technical aspect that consider its benefits, technical issues, feasibility, acoustic impact, sustainability, system and maintenance. On the other hand, creative methods to approach VG are seldom researched upon especially in Malaysia. Hence, this study explores this possibility from the public’s perspectives. The objectives were to identify public’s familiarity and values of VG as PA, and VG attributes to be as a PA. An online survey was used to obtain public’s perspectives on the integration of VG as PA. The target respondents were the public, whereby the link to the survey was sent out to 400 potential respondents. The survey obtained 117 responses, and they were gathered automatically in an Excel spreadsheet. The data were converted into the themes to generate results. Findings yield positive outcomes in terms of the public’s familiarity of the terminologies (i.e. VG and PA), people’s awareness of VG in an urban environment, and the possibilities and potentials of VG to become a PA in Malaysian cities. It means that VG has extended beyond the environmental benefits to also become an art form for people in a city

Split-Half Analysis : Measurement of Validity and Reliability of the Career Counselling Self-Efficacy Scale (CCSES) in Malaysian Public Universities

Self-efficacy is an important aspect in measuring counsellor’s abilities to conduct counselling processes. This study aims to assess the validity and reliability of self-efficacy using the Split-half technique. The Career Counselling Self-Efficacy Scale (SSES) aims to measure the level of counsellor’s readiness to provide career counselling services to clients that covers aspects of knowledge and skills. A quantitative approach was used and data analysed by using the SPSS. The instrument has been translated into Malay and involved a 25 items instrument consisting of five sub-scales related to the counsellor’s efficacy. The analysis using the Split-half approach reported the reliability value for the entire item of Part 1 (0.96) and Part 2 (0.97). The study has inferred that the instrument has a satisfactory level of reliability and can be used in the Malaysian context. The new version of instruments has an impact to the counsellor competency in practice. The counsellor will have a view in terms of their ability to handle career counselling. Aside from curriculum development, career counselling can be improved in line with current need. There are a limited numbers of inventories translated into Malay. The new version of CCSES can minimise the cultural issues faced by counsellors in their practice

Robust estimation methods for fixed effect panel data model having block-concentrated outliers

The Ordinary Least Squares (OLS) is the commonly used method to estimate the parameters of fixed effect panel data model. However, the method is tremendously affected by the presence of outliers. In addressing the problem, we proposed new and improved robust estimators to provide resilient estimates against the most critical outlying values known as block high leverage points (HLPs). Firstly, we proposed robust panel data transformation to be performed around the MM-estimate of location as an alternative to the non-robust centering by the mean. Two robust Within Group estimators known as Robust Within Group MM (RWMM) and Robust Within Group GM (RWGM) are also proposed to be simulated under the MM-centering. Results of simulation study and real data identify RWMM and RWGM to provide more resistant and efficient estimates under MM-centering compare to the existing estimation based on median centering. Not much research has been done on method of detecting HLPs for panel data. Hence, we have proposed Robust Diagnostic-F (RDF) to remedy the problem of masking and swamping in detecting HLPs. Simulation works and numerical examples prove that the newly proposed RDF outperforms existing methods with the lowest rates of swamping. The existing RWGM estimator has shortcoming whereby it is based on Robust Mahalanobis Distance (RMD) based on Minimum Volume Ellipsoid (MVE) which is prone to suffer from swamping effect. To rectify this problem, the RWGM with RDF and RWGM with DRGP are developed by integrating the RDF and existing Diagnostic Robust Generalized Potential (DRGP); respectively, into the algorithm of GM-estimator. Results indicate that the performance of RWGM(RDF) estimator which uses RDF as part of its weighting scheme surpasses other methods under study. To date no work has been focused on robust bootstrapping methods for fixed effect panel data model. Thus, bootstrapping methods known as Diagnostic Bootstrap (Boot-D) and Weighted Bootstrap with RDF (Boot RDF) are also developed to provide resistance bootstrap estimates against block HLPs. In Boot-D, a diagnostic measure is introduced to eliminate any outlier from the sampling plan whereas new re-sampling with probabilities is derived in Boot RDF. In the study, Boot RDF is found to provide robust and superior performance as confirmed by the numerical examples and simulation results. This research also addresses the combined problem of HLPs and heteroskedastic errors for fixed effect panel data model. A two-step robust estimator called Two Step Heteroskedasticity-Outlier (TSHO) is proposed and successfully dampens both problems. This study is considered to be among the first to solve simultaneous problems of heteroskedastic and non-normal errors for panel data. Empirical evidence via simulation experiments and numerical data show TSHO to be persistent under zero or high level of contamination. Standard errors of the beta estimates are also corrected by the newly proposed heteroskedasticity- and outlier- robust standard error or HORSE estimator. Two types of robust weights are introduced in HORSE to protect against large residuals caused by block HLPs and also heteroskedasticity. In the events, simulation results indicate the lowering level of biasness by HORSE. This leads to the final conclusion that HORSE is able to produce less bias standard errors due to the robust weighting schemes introduced in its algorithm

Robust centering in the fixed effect panel data model

In recent years, robust estimators for fixed effect panel data model have been developed to provide alternatives to the least square estimates in the presence of outliers. The robust adaptation involves transformation of data by the median instead of the mean in order to eliminate any unobserved effect. Median centering is chosen due to its robustness, simple derivation and possesses min max property. However, the procedure introduces non-linearity in the data and causes some robust estimators to lose their regression equivariance property. This study proposed MM-centering to provide robust solutions to the Within Group parameter estimates. The numerical results indicate that the proposed methods are more efficient than the existing method