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INDONESIA
FORUM STATISTIKA DAN KOMPUTASI
Published by Institut Pertanian Bogor
ISSN : 08538115     EISSN : -     DOI : -
Core Subject : Education,
Mathematics
Forum Statistika dan Komputasi (ISSN:0853-8115) was published scientific papers in the area of statistical science and the applications. It is issued twice in a year. The papers should be research papers with, but not limited to, following topics: experimental design and analysis, survey methods and analysis, operation research, data mining, statistical modeling, computational statistics, time series and econometrics, and statistics education.
Arjuna Subject : -
Articles 119 Documents
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MODEL OTENTIKASI KOMPOSISI OBAT BAHAN ALAM BERDASARKAN SPEKTRA INFRAMERAH DAN KOMPONEN UTAMA STUDI KASUS : OBAT BAHAN ALAM/FITOFARMAKA PENURUN TEKANAN DARAH Agus Mohamad Soleh; Latifah K. Darusman; Mohamad Rafi
FORUM STATISTIKA DAN KOMPUTASI Vol. 13 No. 1 (2008)
Publisher : FORUM STATISTIKA DAN KOMPUTASI

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Abstract

Komposisi kimia yang terkandung dalam ekstrak obat bahan alam merupakan suatu komposisi yang kompleks, dengan demikian pengujian keotentikannya tidak dapat dilakukan melalui pedekatan tunggal.  Salah satu teknik analisis yang dapat menggambarkan secara menyeluruh karakteristik kimia suatu bahan adalah teknik spektroskopi FTIR. Spektra FTIR dihasilkan dari interaksi antara energi sinar inframerah dan komponen kimia penyusun campuran bahan, sehingga suatu spektra FTIR merupakan indentitas khas campuran tersebut. Keotentikan komposisi suatu obat bahan alam pada studi  ini ditentukan berdasarkan pada analisis komponen utama spektra inframerahnya.  Studi dilakukan pada obat bahan alam/fitofarmaka penurun tekanan darah (Tensigard® : terdiri dari ekstrak seledri dan ekstrak daun kumis kucing). Pengukuran spektra inframerah dilakukan terhadap formula obat yang persentase komposisinya ditentukan melalui simplex lattice design. Selain itu pengukuran spektra inframerah juga dilakukan terhadap formula obat dengan mengganti (adulterasi) ekstrak kumis kucing dengan obat sintetis (reserpin) dan ekstrak sambiloto. Berdasarkan plot antara skor komponen utama pertama dan skor komponen utama kedua menunjukkan plot tersebut dapat digunakan untuk mendeteksi komposisi obat, tetapi tidak dapat mendeteksi adanya adulterasi komposisi oleh bahan lain.   Kata Kunci : model otentikasi fitofarmaka, simplex lattice design, komponen utama, tensigard
PENENTUAN DOMAIN DENGAN TEKNIK VARIOGRAM Aji Hamim Wigena; Utami Dyah Syafitri; Yuan Millafanti
FORUM STATISTIKA DAN KOMPUTASI Vol. 12 No. 2 (2007)
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Abstract

Dalam banyak kesempatan, penyusunan model skoring untuk memprediksi klasifikasi calon nasabah dilakukan menggunakan model regresi logistik dan beberapa model lain.  Proses pengklasifikasian dapat juga dilakukan dengan menerapkan simple naive Bayesian classifier.  Meskipun menggunakan asumsi yang secara umum dilanggar oleh data dan proses komputasi yang jauh lebih sederhana, teknik ini mampu menghasilkan akurasi dugaan yang tidak mengecewakan.  Paper ini memberikan ilustrasi penggunaan simple naive bayesian classifier pada kasus prediksi klasifikasi status kolektibilitas calon nasabah dan membandingkannya dengan model regresi logistik dan generalized additive model.   Kata kunci: simple naive Bayesian classifier
KAJIAN METODE THURSTONE DALAM PENENTUAN ASPEK PENTING PADA SISTEM TRANSAKSI NON TUNAI Hari Wijayanto; Anang Kurnia; Ina Widayanty
FORUM STATISTIKA DAN KOMPUTASI Vol. 12 No. 2 (2007)
Publisher : FORUM STATISTIKA DAN KOMPUTASI

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Abstract

Data persepsi sudah sangat umum diukur dalam skala ordinal.  Thurstone memperkenalkan metode untuk mengolah data ordinal, diantaranya adalah metode Thurstone, metode equal appearing intervals, dan metode successive intervals. Prinsip dasar metode-metode tersebut adalah mentransformasi data dari skala ordinal menjadi interval agar relevan dalam melakukan interpretasi. Selain itu, metode tersebut dapat menilai peringkat suatu atribut dan mengukur seberapa besar perbedaan kepentingan suatu atribut terhadap atribut lainnya. Pada kasus penilaian tingkat kepentingan responden dalam menggunakan transaksi non tunai, hasil uji kesesuaian model pada metode Thurstone dan metode successive intervals menyatakan bahwa model telah cukup baik menggambarkan kondisi data sebenarnya dengan tingkat ketidaksesuaian masing-masing sebesar 2.3% dan 4.5%.  Metode Thurstone relatif tidak sensitif terhadap perubahan bobot atau skala penilaian pada suatu atribut. Metode Thurstone hanya melihat bagaimana hasil penilaian berpasangan antara dua atribut, namun tidak mampu melihat perbedaan penilaian yang diberikan oleh responden terhadap atribut-atribut tersebut. Penilaian tingkat kepentingan dalam menggunakan transaksi non tunai memberikan hasil tiga peringkat tingkat kepentingan paling tinggi dalam melakukan transaksi non tunai secara berutut-turut adalah aspek tingkat kemudahan atau aksesibilitas, tingkat keamanan, dan kecepatan transaksi. Kenyamanan merupakan aspek yang tingkat kepentingannya paling rendah dibandingkan atribut lain. Kata kunci : Metode Thurstone, Transaksi Non Tunai
KONSISTENSI RESPONDEN DALAM MENGEVALUASI PROFIL PRODUK PADA ANALISIS KONJOIN Utami Dyah Syafitri; Hari Wijayanto; Yuni Suci Kurniawati
FORUM STATISTIKA DAN KOMPUTASI Vol. 12 No. 2 (2007)
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Abstract

Salah satu non sampling error dalam suatu survey adalah ketidakkonsistenan jawaban yang diberikan oleh responden terutama jika diminta untuk memberikan prioritas terhadap profil suatu produk. Hal tersebut berkaitan dengan alat ukur (kuesioner) yang digunakan. Dalam analisis konjoint, evaluasi preferensi terhadap suatu produk dilakukan dengan memberikan penilaian (rating) dan mengurutkan (ranking) profil-profil suatu produk. Responden dikatakan konsisten apabila hasil analisis konjoin per individu dari data rating dan ranking menunjukkan urutan tingkat kepentingan atribut yang sama dari dua metode pengukuran tersebut. Sebagai bahan evaluasi terhadap ketidakkonsistenan jawaban responden, dalam penelitian ini digunakan studi kasus preferensi mahasiswa IPB dalam memilih mata kuliah pilihan. Pengambilan sampel dilakukan secara purposive. Dari hasil survey, secara umum dapat dikatakan responden konsisten dalam mengevaluasi stimuli dengan metode rating dan ranking. Sedangkan apabila ditinjau dari sisi masing-masing individu diperoleh sekitar 43% responden yang dapat mengevaluasi stimuli dengan metode rating dan ranking secara konsisten. Kekonsistenan jawaban responden dipengaruhi oleh lamanya waktu yang diperlukan untuk evaluasi produk, sikap dan kesungguhan dalam menjawab, serta pribadi yang serius (ditunjukkan oleh prilaku yang tidak gemar bermain games). Kata kunci : konjoint, rating, ranking, kekonsistenan
A SUMMARIZATION OF BAYESIAN ASPECTS OF SMALL AREA ESTIMATION Dian Handayani
FORUM STATISTIKA DAN KOMPUTASI Vol. 12 No. 2 (2007)
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Abstract

Bayesian approach in Small Area Estimation (SAE), namely Empirical Bayes (EB) and Hierarchical Bayes (HB), will be described. EB approach in SAE has been given considerable attention by some practitioners because it does not require specification of the prior distribution for model parameters and it is usually obtained in a closed form. However, an accurate measure of uncertainty of EB estimator can not be obtained unlike HB estimator in which its uncertainty can be measured exactly. On the other hand, HB approach requires subjective prior distribution for model parameters and it is usually not easy to be specified in practice especially for public policy. Keywords : small area estimation, empirical bayes, hierarchical bayes
LASSO : SOLUSI ALTERNATIF SELEKSI PEUBAH DAN PENYUSUTAN KOEFISIEN MODEL REGRESI LINIER Agus Mohamad Soleh; _ Aunuddin
FORUM STATISTIKA DAN KOMPUTASI Vol. 18 No. 1 (2013)
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Abstract

A new method, known as LASSO, has recently developed for selections and shrinkage linear regression methods. The method gives an alternative solution on high correlated data between independent variables, where the least squares produces high variance. Based on simulation this method is not better than forward selection (in the case the parameters contains many zero values) and ridge regression (in the case all parameter values close to zero). Unknowing the true parameter and consistency estimates for all conditions that put the LASSO is better than ridge or forward selection.Keywords : LASSO, least square, forward selection, ridge, cross validation
SURVIVAL ANALYSIS OF CUSTOMER IN POSTPAID TELECOMMUNICATION INDUSTRY Doni Suhartono; Asep Saefuddin; I Made Sumertajaya
FORUM STATISTIKA DAN KOMPUTASI Vol. 18 No. 1 (2013)
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Abstract

Currently, the business competition in mobile telecommunication industry among providers in Indonesia is tighter and it has given rise to a phenomenon of customer defection which has serious consequences for the business performance. In the current circumstances, customers are faced numerous options to be selected that probably cause them at risk to get churn. Therefore, it becomes one of the challenges encountered by Division of Loyalty and Retention to makes the efforts of decreasing customer defection. So that it is important conducting a model of churn practically applied to predict tendency of customer churn and also recognizing the prognostic factors influence customer churn. Survival analysis modelling, such as Cox’s proportional hazard model, was very successful in previous research, which investigatedthe relationship between survival time and possible prognostic factors. Based on the research, Cox’s proportional hazard model of customer lifetime is effective to distinguish relative risk between churn customers and others, and also between which loyal customers and with other short time customers with their significant prognostic factors. Afterwards the simulation of the survival probability estimated over time with particular possible combination of the most significant characteristics affecting tendency of churn, are able to predict such information of lifetime to churn event and compare the survival performance of one another. Finally, the results of this research is able to yield simple, helpful and applicable results as the principle of taking decission for optimizing their customer retention and/or treatment resources in their customer retention efforts for the company.Key words : Churn, Cox’s proportional hazard model, customer retention, survival analysis and telecommunication industry.
PENDEKATAN KUADRAT TERKECIL PARSIAL KEKAR UNTUK PENANGANAN PENCILAN PADA DATA KALIBRASI Enny Keristiana Sinaga; Anik Djuraidah; Aji Hamim Wigena
FORUM STATISTIKA DAN KOMPUTASI Vol. 18 No. 1 (2013)
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Abstract

The serious problems in the calibration of multivariate estimation are multicollinearity and outliers. Partial Least Squares (PLS) is one of the statistical method used in chemometrics, to handle high or perfect multicollinearity in independent variables. Straightforward Implementation Partial Least Squares (SIMPLS) is the extension of PLS regression proposed by De Jong (1993). The SIMPLS algorithm is based on the empirical cross-variance matrix between the independent variables and the regressors. This method does not resistant toward outlier observations. Robust PLS method is used to handle the multicollinearity and outliers in the data sets. This method can be classified in two groups, there are iteratively reweighting technique and robustication of covariance matrix. Partial Regression-M (PRM) method is one of the robust PLS methods used the idea of iteratively reweighting technique that proposed by Serneels et al. (2005). Robust SIMPLS (RSIMPLS) method is one of the robust PLS methods used the idea of robustication of covariance that proposed by Huber and Branden (2003). A modified RSIMPLS used M estimator with the Huber weight function called RSIMPLS-M was proposed by Ismah (2010). These two methods (RSIMPLS-M and PRM) are applied to Fish data (Naes 1985) to know their performances. The research results indicated that the values of R2 and RMSEP of RSIMPLS-M are higher than those of PRM method. Whereas based on the confidence interval estimation of the regression coefficients by jackknife method, estimation of PRM is narrower than that RSIMPLS-M method. Therefore RSIMPLS-M method is better than PRM method for prediction, whereas PRM method is better than RSIMPLS-M method for estimation.Keywords : Partial least squares regression robust (PLSRR), partial robust M-regression (PRM), straightforward implementation partial least squares robust (RSIMPLS)
BOOTSTRAP PARAMETRIK DAN NONPARAMETRIK UNTUK PENDUGAAN KUADRAT TENGAH GALAT DALAM STATISTIK AREA KECIL DENGAN RESPON BERSEBARAN LOGNORMAL Cempaka Putri; Khairil Anwar Notodiputro; La Ode Abdul Rahman
FORUM STATISTIKA DAN KOMPUTASI Vol. 18 No. 1 (2013)
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Abstract

Small area estimation is needed to obtain information in small area, that is area containing small size of sample. Direct estimation in small area will result in large variance. Indirect estimation is the solution, with involves auxiliary data from related area or another survey in parameter estimation. One of the prolems found in using this procedure is low precision of Mean Square Error (MSE) estimate caused by non-normal distribution. Parameter of concern in this study is per capita expenditure of village in Bogor regency. Per capita expenditure is non-normal distribution. MSE estimator with bootstrap method has the advantage of potential robustness against sampling from non- normal distribution. Therefore this study used bootstrap method, such as parametric bootstrap and nonparametric bootstrap, in MSE estimation. Generally, the result showed that the MSE estimate of the parametric bootstrap smaller than the nonparametric bootstrap. Both method have better precision, so that they can repair the result of direct estimation.Keywords : small area estimation, parametric bootstrap, nonparametric bootstrap
DETEKSI DINI RISIKO KREDIT MELALUI RATING TRANSITION STOCHASTIC MATRIX DAN VALUE AT RISK (Early Detection of Credit Risk Through Rating Transition Stochastic Matrix and Value at Risk) _ Haryono; Sri Pingit Wulandari; Sri Mumpuni Retnaningsih
FORUM STATISTIKA DAN KOMPUTASI Vol. 17 No. 1 (2012)
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Abstract

Credit risk is the risk occurs when the debtors fail to meet their obligation in accordance with agreed term to the bank. This research is made to analyze the credit risk for industrial and trade sector in Bank X, both sectors contribute about 80% loan credit. The calculation of the VaR 95% used Markov Chain regular and ergodic and adjusted by macro economic variable which significance influence the movement of those quality rating. The result of Markov chain for industrial sector show that the ability debtor increase for repay the loan in the long run but for trade sector became worst. The VaR 95% results for industrial sector is Rp 2,17 billion or about 3,27% and for trade sector is Rp 4,46 billion or about 2,03% from outstanding credit those sectors. This results is not appropriate with the New Basel Capital Accord which recomennded to allocate capital 8% from outstanding credit to cover credit risk. The calculation of the TVaR 95% for industrial sector is Rp 4,89 billion or about 7,38% and for trade sector is Rp 16,60 billion or about 7,55% from outstanding credit both sectors. For the TVaR 95% portofolio give the results is Rp 18,99 billion or about 6,5% from outstanding credit.Keywords : Credit Risk, Markov chain, Regression, Macroeconomics, VaR, TVaR, Portofolio Risk.

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