Kriterium Majmuk bagi Penganggaran Parameter dan Peramalan Sambutan

A multiplicative compound criterion is used to generate a unique design which can simultaneously fulfil two important objectives: parameter estimation and response prediction. Thegene ralised variance criterion is chosen for the first objectivec while the variance function or the integrated variance criterion is fOr the second

Hodges Lehmann estimator for robust design using Dual Response Surface Approach

In this paper, we proposed the usage of the robust Hodges Lehmann estimator (HLE) as a location measure in the construction of optimal designs using the Dual Response Surface Approach (DRSA) where the location and scale measures were incorporated simultaneously into the model. The performance of six models with different pairs of location and scale estimators were compared. The results from a simulation study showed that for the non-normal and normal distribution with contaminated data, the model using HLE and inter-quartile range (IQR) performed better than the pair of the sample median and IQR as achieved by Park and Cho (2002)

What drives house price in Malaysia? In search of an alternative pricing benchmark for Islamic home financing

The current practise of the Islamic banks to rely on market interest rate as pricing benchmark for their home financing products has been a subject of intense debate among many parties. Muslim scholars have warned that it is highly discouraged as it could lead to a possible convergence between the practices of the Islamic and conventional banks. This paper intends to address the financing issues in the discussion of human settlement or housing policy by presenting the determinants for house price index as well as looking into the possibility of adopting the House Price Index (HPI) to replace the market interest rate as a pricing benchmark for the Islamic home financing. The study applies Auto-Regressive Distributed Lag (ARDL) method on a model comprising HPI as the dependent variable and a set of independent variables consisting of economic, housing demand and housing supply factors. The findings lead to the formulation of recommendations as a way forward for the Islamic banking industry in particular, and the economy in general. This will require a paradigm shift from basic financing products to a more holistic approach which integrates supply of housing factors, as well as urban planning and urban finance, with human rights and recognizes the need to place and shelter people

A stochastic joint model for longitudinal and survival data with cure patients

Many medical investigations generate both repeatedly-measured (longitudinal) biomarker and survival data. One of complex issues arises when investigating the association between longitudinal and time-to-event data when there are cured patients in the population, which leads to a plateau in the survival function S(t) after sufficient follow-up. Thus, usual Cox proportional hazard model Cox (1972) is not applicable since the proportional hazard assumption is violated. An alternative is to consider survival models incorporating a cure fraction. In this paper we present a new class of joint model for univariate longitudinal and survival data in presence of cure fraction. For the longitudinal model, a stochastic Integrated Ornstein-Uhlenbeck process will be presented. For the survival model a semiparametric survival function will be considered which accommodate both zero and non-zero cure fractions of the dynamic disease progression. Moreover, we consider a Bayesian approach which is motivated by the complexity of the model. Posterior and prior specification needs to accommodate parameter constraints due to the nonnegativity of the survival function. A simulation study is presented to evaluate the performance of this joint model

Bayesian approach for joint longitudinal and time-to-event data with survival fraction

Many medical investigations generate both repeatedly-measured(longitudinal) biomarker and survival data. One of complex issue arises when investigating the association between longitudinal and time-to-event data when there are cured patients in the population, which leads to a plateau in the survival function S(t) after sufficient follow-up. Thus, usual Cox proportional hazard model [11] is not applicable since the proportional hazard assumption is violated. An alternative is to consider survival models incorporating a cure fraction. In this paper, we present a new class of joint model for univariate longitudinal and survival data in presence of cure fraction. For the longitudinal model, a stochastic Integrated Ornstein-Uhlenbeck process will present, and for the survival model a semiparametric survival function will be considered which accommodate both zero and non-zero cure fractions of the dynamic disease progression. Moreover, we consider a Bayesian approach which is motivated by the complexity of the model. Posterior and prior specification needs to accommodate parameter constraints due to the non-negativity of the survival function. A simulation study is presented to evaluate the performance of the proposed joint model

Cure fraction, modelling and estimating in a population-based cancer survival analysis

In population-based cancer studies, cure is said to occur when the mortality (hazard)rate in the diseased group of individuals returns to the same level as that expected in the general population. The optimal method for monitoring the progress of patient care across the full spectrum of provider settings is through the population-based study of cancer patient survival, which is only possible using data collected by population-based cancer registries. The probability of cure, statistical cure, is defined for a cohort of cancer patients as the percent of patients whose annual death rate equals the death rate of general cancer-free population. Recently models have been introduced, so called cure fraction models, that estimates the cure fraction as well as the survival time distribution for those uncured. The colorectal cancer survival data from the Surveillance, Epidemiology and End Results (SEER) program, USA, is used. The aim is to evaluate the cure fraction models and compare these methods to other methods used to monitor time trends in cancer patient survival, and to highlight some problems using these models

A Semiparametric Joint Model for Longitudinal and Time-to- Event Univariate Data in Presence of Cure Fraction

Many medical investigations generate both repeatedly-measured (longitudinal)biomarker and survival data. One of complex issue arises when investigating the association between longitudinal and time-to-event data when there are cured patients in the population, which leads to a plateau in the survival function S(t) after sufficient follow-up. Thus, usual Cox proportional hazard model Cox (1972) is not applicable since the proportional hazard assumption is violated. An alternative is to consider survival models incorporating a cure fraction. In this paper we present a new class of joint model for univariate longitudinal and survival data in presence of cure fraction. For the longitudinal model, a stochastic Integrated Ornstein-Uhlenbeck process will present, and for the survival model a semiparametric survival function will be considered which accommodate both zero and non-zero cure fractions of the dynamic disease progression. Moreover, we consider a Bayesian approach which is motivated by the complexity of the model. Posterior and prior specification needs to accommodate parameter constraints due to the nonnegativity of the survival function. A simulation study is presented to evaluate the performance of this joint model

Kinetics and thermodynamic for sorption of arsenate by lanthanum-exchanged zeolite

Zeolites are crystalline, hydrated aluminosilicate containing exchangeable alkaline and alkaline earth cations in their structural frameworks. Since zeolites have permanent negative charges on their surfaces, they have no affinity for anions. However recent studies have shown that modification of zeolites with certain surfactants or metal cations yield sorbents with a strong affinity for many anions. In this paper, modification of zeolites (zeolite A, X and ZSM5) were performed by exchange of naturally occurring cations with lanthanum ion that forms low solubility arsenate salt. The exchanged zeolites were used to sorb arsenate from aqueous solution. Among parameters investigated were effect of pH, arsenate initial concentrations, contact time and temperature. The maximum exchanged capacity of La(III) ion was obtained when using solution with initial pH of 4. Zeolite X gives the highest La(III) exchanged capacity compared to other zeolites. The results showed that As(V) sorption by La-zeolites occurred at about pH 6.5 and increased as pH increased and reaching maximum at equilibrium pH about 7.8. On the other hand, almost no arsenate sorption occurred on unexchanged zeolites. This indicates that La(III) ion on the exchanged zeolites is taking part on the As(V) sorption via surface precipitation. The results also showed that the sorption capacities increased with increasing initial As(V) concentrations. The sorption followed Langmuir model with maximum sorption capacities of 0.41, 0.21 and 0.19 mmol/g at 25°C for La exchanged zeolite X (La-ZX), La exchanged zeolite ZSM5 (La -ZSM) and La exchanged zeolite A (La-ZA), respectively. The amo unts of sorption of As(V) by La exchanged zeolite increased as temperature increased from 25 to 70°C indicating that the process is endothermic. The free energy changes (DG°) for the sorption at 25°C were -10.25, -9.65 and -8.49 kJ/mol for La-ZX, La -ZSM and La-ZA, respectively. The negative values of DG° meant that the sorption of As(V) ions on La-exchanged zeolite was spontaneous, perhaps because the La(III) had high affinity towards the arsenic ion as indicated by a low Ksp value of of lanthanum arsenate. A slightly positive entropy change for sorption of As(V) ion on La-exchanged zeolite could be due to fixation of the ions on the La(III) exchange sites that was randomly distributed on the sorbents. The kinetics study showed that the As(V) sorption followed first order kinetic model. The first-order kinetic constants for the sorption are 2.77x10-3, 2.25x10-3 and 1.60x10-3 min-1 for La-ZX, La -ZSM and La-ZA, respectively

Sorption of arsenate by stannum(IV)-exchanged zeolite P

Zeolites are crystalline, hydrated aluminosilicate containing exchangeable alkaline and alkaline earth cations in their structural frameworks. Previous studies have shown that modification of zeolites with an active metal cations yield sorbents with a strong affinity for certain anions. Recently hydrous tin oxide was found effective to remove arsenic anions from aqueous solution. In this study, sodium ion of zeolite P was exchanged with stannum(IV) and used for sorption of arsenate (As(V)) ion. Among parameters investigated were effect of pH, As(V) initial concentrations, contact time, temperature and effect of foreign ions. The results show that As(V) sorption by stannum(IV) exchanged zeolite P (SnZP) was maximum at about pH 2. The sorption capacities increase with increasing initial As(V) concentrations and follows Langmuir model with maximum sorption capacity of 83.33 mg/g at 25°C. The sorption capacity of As(V) by SnZP increased as temperature increases from 25 to 70°C showing that the process is endothermic with DH° value of 83.84 kJ mol-1. The free energy change (DG°) for the sorption was negative showing that the sorption of As(V) ions is spontaneous. The kinetics study shows that the As(V) sorption follows second order kinetic model. The free energy (E) was 12.91 kJ mol-1 which shows the sorption is an ion-exchange process. The As(V) sorption by SnZP was not affected by the presence sulphate, chloride, nitrate and carbonate but was significantly reduced by phosphate

A cyclic voltammetric synthesis of ZnS thin films using triethanolamine as a complexing agent

ZnS thin films have been synthesized by means of cyclic voltammetry technique. An aqueous solution of zinc chloride was used as Zn2+ source, sodium thiosulfate as S2- source and triethanolamine as complexing agent for depositing ZnS thin films. The influence of complexing agent on the formation and properties of zinc sulphide thin films was investigated. Structure and surface morphology of thin films were characterized by X-ray diffraction and atomic force microscopy, respectively. The band gap energy and type of optical transition were determined from optical absorbance data. The band gap energy varies from 1.7 to 2.5 eV for the films prepared at different amounts of triethanolamine. XRD data indicate that the thin film deposited in presence of triethanolamine is polycrystalline in nature with cubic phase. Increase in amount of triethanolamine (5 ml) in electrochemical bath leads film is homogeneous, well covered to the substrate and exhibits higher absorption characteristic. We can conclude that the amount of complexing agent could affect the structure, surface morphology and optical properties of deposits. The good quality of zinc sulphide thin film could be prepared in the presence of triethanolamine