Purhadi Purhadi

Purhadi Purhadi

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Research Focus & Metrics

Academic Career Length

7Years (2020-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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TSTiodora Hadumaon Siagian
Tiodora Hadumaon Siagian
PPPurhadi Purhadi
Purhadi Purhadi
SSSuhartono Suhartono
Suhartono Suhartono
HRHamonangan Ritonga
Hamonangan Ritonga

14 May 2020 in Symmetry
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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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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.

21 January 2023 in Mathematics
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MRMarisa Rifada
Marisa Rifada
VRVita Ratnasari
Vita Ratnasari
PPPurhadi Purhadi
Purhadi Purhadi
Logistic regression is one of statistical methods that used to analyze the correlation between categorical response variables and predictor variables which are categorical or continuous. Many studies on logistic regression have been carried out by assuming that the predictor variable and its logit link function have a linear relationship. However, in several cases it was found that the relationship was not always linear, but could be quadratic, cubic, or in the form of other curves, so that the assumption of linearity was incorrect. Therefore, this study will develop a bivariate polynomial ordinal logistic regression (BPOLR) model which is an extension of ordinal logistic regression, with two correlated response variables in which the relationship between the continuous predictor variable and its logit is modeled as a polynomial form. There are commonly two correlated response variables in scientific research. In this study, each response variable used consisted of three categories. This study aims to obtain parameter estimators of the BPOLR model using the maximum likelihood estimation (MLE) method, obtain test statistics of parameters using the maximum likelihood ratio test (MLRT) method, and obtain algorithms of estimating and hypothesis testing for parameters of the BPOLR model. The results of the first partial derivatives are not closed-form, thus, a numerical optimization such as the Berndt–Hall–Hall–Hausman (BHHH) method is needed to obtain the maximum likelihood estimator. The distribution statistically test is followed the Chi-square limit distribution, asymptotically.

16 February 2021 in Symmetry
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PPPurhadi Purhadi
Purhadi Purhadi
M. FathurahmanM. Fathurahman
M. Fathurahman
This article provides a bivariate binary logit model and statistical inference procedures for parameter estimation and hypothesis testing. The bivariate binary logit (BBL) model is an extension of the binary logit model that has two correlated binary responses. The BBL model responses were formed using a 2 × 2 contingency table, which follows a multinomial distribution. The maximum likelihood and Berndt–Hall–Hall–Hausman (BHHH) methods were used to obtain the BBL model. Hypothesis testing of the BBL model contains the simultaneous test and the partial test. The test statistics of the simultaneous test and the partial test were determined using the maximum likelihood ratio test method. The likelihood ratio statistics of the simultaneous test and the partial test were approximately asymptotically chi-square distributed with 3p degrees of freedom. The BBL model was applied to a real dataset, and the BBL model with the single covariate was better than the BBL model with multiple covariates.

14 June 2018 in Journal of Physics: Conference Series
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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.