Purhadi Purhadi

Dr. Purhadi Purhadi

Institut Teknologi Sepuluh Nopember (ITS)
orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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16 October 2013 in Natural Hazards
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Journal Article
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TSTiodora Hadumaon Siagian
Tiodora Hadumaon Siagian
PPPurhadi Purhadi
Purhadi Purhadi
SSSuhartono Suhartono
Suhartono Suhartono
HRHamonangan Ritonga
Hamonangan Ritonga

14 May 2020 in Symmetry
Verified
Journal Article
Open access
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ARAnita Rahayu
Anita Rahayu
PPPurhadi Purhadi
Purhadi Purhadi
SUSutikno
Sutikno
DPDedy Dwi Prastyo
Dedy Dwi Prastyo
Gamma distribution is a general type of statistical distribution that can be applied in various fields, mainly when the distribution of data is not symmetrical. When predictor variables also affect positive outcome, then gamma regression plays a role. In many cases, the predictor variables give effect to several responses simultaneously. In this article, we develop a multivariate gamma regression (MGR), which is one type of non-linear regression with response variables that follow a multivariate gamma (MG) distribution. This work also provides the parameter estimation procedure, test statistics, and hypothesis testing for the significance of the parameter, partially and simultaneously. The parameter estimators are obtained using the maximum likelihood estimation (MLE) that is optimized by numerical iteration using the Berndt–Hall–Hall–Hausman (BHHH) algorithm. The simultaneous test for the model’s significance is derived using the maximum likelihood ratio test (MLRT), whereas the partial test uses the Wald test. The proposed MGR model is applied to model the three dimensions of the human development index (HDI) with five predictor variables. The unit of observation is regency/municipality in Java, Indonesia, in 2018. The empirical results show that modeling using multiple predictors makes more sense compared to the model when it only employs a single predictor.

7 June 2017 in Journal of Physics: Conference Series
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Conference Paper
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AAAnik Anekawati
Anik Anekawati
BOBambang Widjanarko Otok
Bambang Widjanarko Otok
PPPurhadi Purhadi
Purhadi Purhadi
SUSutikno
Sutikno
Research in education often involves a latent variable. Statistical analysis technique that has the ability to analyze the pattern of relationship among latent variables as well as between latent variables and their indicators is Structural Equation Modeling (SEM). SEM partial least square (PLS) was developed as an alternative if these conditions are met: the theory that underlying the design of the model is weak, does not assume a certain scale measurement, the sample size should not be large and the data does not have the multivariate normal distribution. The purpose of this paper is to compare the results of modeling of the educational quality in high school level (SMA/MA) in Sumenep Regency with structural equation modeling approach partial least square with three schemes estimation of score factors.This paper is a result of explanatory research using secondary data from Sumenep Education Department and Badan Pusat Statistik (BPS) Sumenep which was data of Sumenep in the Figures and the District of Sumenep in the Figures for the year 2015. The unit of observation in this study were districts in Sumenep that consists of 18 districts on the mainland and 9 districts in the islands. There were two endogenous variables and one exogenous variable. Endogenous variables are the quality of education level of SMA/MA (Y1) and school infrastructure (Y2), whereas exogenous variable is socioeconomic condition (X1). In this study, There is one improved model which represented by model from path scheme because this model is a consistent , all of its indicators are valid and its the value of Rsquare increased which is: Y 1 =0.651Y 2. In this model, the quality of education influenced only by the school infrastructure (0.651). The socioeconomic condition did not affect neither the school infrastructure nor the quality of education. If the school infrastructure increased 1 point, then the quality of education increased 0.651 point. The quality of education had an R 2 of 0.418, which indicates that 41.8 percent of variance in the quality of education is explained by the school infrastructure, the remaining 58.2% is explained by the other factors which were not investigated in this work.

14 June 2018 in Journal of Physics: Conference Series
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Conference Paper
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WWwibawati wibawati
wibawati wibawati
MMMuhammad Mashuri
Muhammad Mashuri
PPPurhadi Purhadi
Purhadi Purhadi
IRIrhamah
Irhamah
MAMuhammad Ahsan
Muhammad Ahsan
One of the most useful tool in Statistics Process Control is control chart. This technique has been used widely in industry and services. One of the most simple attribute control chart is p chart, when the item classified into to categories. In its development, if each item of quality characteristics classify in more than two categories multinomial control chart more appropriate. The classify such as Excellent, Good, Fair and Bad. However, if there is vagueness of the classification for each item, the fuzzy multinomial control chart is more appropriately used. By using triangular fuzzy number to calculate the representative value and simulation study, the control chart will be evaluated based on the value of average run length. For small shift of parameter pi , the value of average run length when the process is in control closed to 370 and when the process out of control the value of average run length are decrease. Based on this this value, it shown that the Fuzzy Multinomial control chart is sensitive.

20 October 2020 in Symmetry
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Journal Article
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SMSelvi Mardalena
Selvi Mardalena
PPPurhadi Purhadi
Purhadi Purhadi
JPJerry Dwi Trijoyo Purnomo
Jerry Dwi Trijoyo Purnomo
DPDedy Dwi Prastyo
Dedy Dwi Prastyo
Multivariate Poisson regression is used in order to model two or more count response variables. The Poisson regression has a strict assumption, that is the mean and the variance of response variables are equal (equidispersion). Practically, the variance can be larger than the mean (overdispersion). Thus, a suitable method for modelling these kind of data needs to be developed. One alternative model to overcome the overdispersion issue in the multi-count response variables is the Multivariate Poisson Inverse Gaussian Regression (MPIGR) model, which is extended with an exposure variable. Additionally, a modification of Bessel function that contain factorial functions is proposed in this work to make it computable. The objective of this study is to develop the parameter estimation and hypothesis testing of the MPIGR model. The parameter estimation uses the Maximum Likelihood Estimation (MLE) method, followed by the Newton–Raphson iteration. The hypothesis testing is constructed using the Maximum Likelihood Ratio Test (MLRT) method. The MPIGR model that has been developed is then applied to regress three response variables, i.e., the number of infant mortality, the number of under-five children mortality, and the number of maternal mortality on eight predictors. The unit observation is the cities and municipalities in Java Island, Indonesia. The empirical results show that three response variables that are previously mentioned are significantly affected by all predictors.

5 April 2020 in Symmetry
Verified
Journal Article
Open access
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WWwibawati wibawati
wibawati wibawati
MMMuhammad Mashuri
Muhammad Mashuri
PPPurhadi Purhadi
Purhadi Purhadi
IIIrhamah Irhamah
Irhamah Irhamah
In the present paper, we develop a fuzzy bivariate Poisson (FBP) control chart based on a fuzzy c chart. The FBP chart is used to monitor the sum of the nonconformities of each quality characteristic. There are two contributions of this work. First, we propose a new fuzzy parameter estimation to create a triangular fuzzy number (TFN). Second, our control chart is flexible, because we involve the α c u t to measure the level of tightness of inspection. Furthermore, the statistic of FBP is being able to visualise the monitoring process in a graphical form. In addition, the simulation study indicates that the performance of our proposed chart, based on average run length (ARL), is more sensitive than the performance of a conventional bivariate Poisson (BP) chart. Moreover, an illustration example shows that the FBP chart has relatively more sensitive performance compared to the conventional BP chart.