Articles

PRE-PROCESSING PADA DATA KALIBRASI RIMPANG JAHE UNTUK MENINGKATKAN KEBAIKANMODEL Arnita, Arnita; Saefuddin, Asep; Notodiputro, Khairil Notodiputro Anwar
STATISTIKA: Forum Teori dan Aplikasi Statistika Vol 4, No 2 (2004)
Publisher : Program Studi Statistika Unisba

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Gejala-gejala aneh dan tidak diharapkan sering terjadi pada dunia nyata. Hal ini juga terjadi pada kemometrik khususnyapada data kalibrasi. Ketidak sesuaian model yang akan mencerminkan respon aslinya dapat disebabkan oleh adanya outlier,bentuk data yang sangat tidak linier, multikolinier, dan lain-lain. Dalam tulisan ini akan ditunjukkan teknik untukmengatasi permasalahan-permasalahan tadi dengan melakukan reduksi peubah, pendeteksian outlier dan transformasispektroskopi. Dapat ditunjukkan bahwa dengan melakukan pengendalian terhadap permasalahan-permasalahan di atasdapat mereduksi KTG (Kuadrat Tengah Galat) dan meningkatkan ketepatan model sampai 30 %.
ANALYZING THE CONSUMER’S RICE PRICE USING MULTIPLE LINEAR REGRESSION AND X-12 ARIMA Kusumaningrum, Dian; Saefuddin, Asep; Kurnia, Anang
STATISTIKA: Forum Teori dan Aplikasi Statistika Vol 4, No 2 (2004)
Publisher : Program Studi Statistika Unisba

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Rice is one of the main foods in Indonesia. A change of rice price will cause a major effect in the lives of consumers. Onthe other hand, there are so many factors that influence the rice price. Thus finding key factors which are significant to therice price, as well as forecasting the consumer’s rice price are needed in order to maintain the stabilization of rice price.The second objective is to find key factors which influence the rice price by using multiple linear regression models. Theparameters were estimated by ordinary least square methods. There are 6 variables that are significant at α=5%, which arethe consumer’s rice price at the previous period, rice production at the current and previous period, farmer’s GKP price,realization of domestic stock, and total rice import. The rice price will increase if the GKP price and realization of domesticstock increase whereas total rice import and the consumer’s rice price at the previous period have negative influencestowards the rice price. In this model rice production at the current and previous period have positive signs, contradictory tothe microeconomic theory where when the rice production increases, there will be an excess supply and the price will drop.That condition will occur only if the commodity is a free commodity and the rice is at the sufficiency level but inIndonesia, rice is affected by the government’s policy and the rice productivity is left behind by the demand. Forecastingthe consumer’s rice price for the next five years was the last objective of this research. ARIMA Box–Jenkins Method, X-12ARIMA, Winter’s Method, and Trend Analysis were compared to find the best statistical model to forecast the consumer’srice price. X-12 ARIMA turns out to be the best method because it has the smallest MAPE, MAD, and MSD value. Thisresult is a satisfactory because according to Findley et al. (1998) X-12 ARIMA has the capability to adjust seasonal andtrading day factors which usually causes fluctuations in an economic time series data. Besides that, the X-12 ARIMAmethod also enhances the lack of other forecasting techniques used in this research to add regression effects. TheregARIMA makes it possible to add the user defined parameters, in this case the length of month parameter. The length ofmonth parameter rescales the monthly observation by a weight corresponding to the month relative length with respect tothe average length. The seasonal adjusted data from the original time series data is aimed to simplify the data withoutloosing important information.PDF
Pemodelan Daya Tahan Mahasiswa Putus Kuliah pada Pendidikan Tinggi Jarak Jauh dengan Regresi Cox Saefuddin, Asep; Ratnaningsih, Dewi Juliah
STATISTIKA: Forum Teori dan Aplikasi Statistika Vol 8, No 1 (2008)
Publisher : Program Studi Statistika Unisba

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Dalam penelitian ini daya tahan mahasiswa didefinisikan sebagai kemampuannya untuk terusberstatus mahasiswa aktif atau tidak putus kuliah. Tingkat putus kuliah pada perguruan tinggijarak jauh (PTJJ) seperti UT merupakan salah satu contoh data yang mengandung data tersensor.Penelitian mengenai daya tahan belajar mahasiswa PTJJ telah banyak dilakukan, namun data putuskuliah tidak dipandang sebagai data tersensor. Dalam penelitian ini data putus kuliah dipandangsebagai data tersensor jenis 1 (sensor waktu sebelah kanan). Regresi Cox dipergunakan untukmengidentifikasi faktor-faktor yang mempengaruhi mahasiswa putus kuliah di UT.Dari pemodelan inisecara umum ditemukan bahwa mahasiswa UT banyak mengalami putus kuliah.Peubah penjelasyang berpengaruh nyata terhadap daya tahan belajar mahasiswa UT adalah: jenis kelamin, usia,indeks prestasi (IP), indeks prestasi kumulatif (IPK), status cuti akademik, jurusan asal (latarbelakang pendidikan formal), dan status pekerjaan mahasiswa.
The Beta-Binomial Multivariate Model for Correlated Categorical Data Hajarisman, Nusar; Saefuddin, Asep
STATISTIKA: Forum Teori dan Aplikasi Statistika Vol 8, No 1 (2008)
Publisher : Program Studi Statistika Unisba

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Over the past year, a significant amount of research has explored the logistic regression models foranalyzing correlated categorical data. In these models, it is assumed that the data occur in clusters,where individuals within each cluster are correlated, but individuals from different clusters areassumed independent. A commonly used in modeling correlated categorical univariate data is toassume that individual counts are generated from a Binomial distribution, with probabilities varybetween individuals according to a Beta distribution. The marginal distribution of the counts is thenBeta-Binomial. In this paper, a generalization of the model is made allowing the number ofrespondent m, to be random. Thus both the number units m, and the underlying probability vectorare allowed to vary. We proposed the model for correlated categorical data, which is generalized toaccount for extra variation by allowing the vectors of proportions to vary according to a Dirichletdistribution. The model is a mixture distribution of multinomial and Dirichlet distribution, and wecall the model as the beta-binomial multivariate model.
The Influence of Family Strength on the Quality of Pregnancy Sunarti, Euis; Syarief, Hidayat; ., Hardinsyah; Megawangi, Ratna; Saefuddin, Asep; ., Husaini
Media Gizi dan Keluarga Vol 27, No 1 (2003): Media Gizi dan Keluarga
Publisher : Media Gizi dan Keluarga

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The Objectives of this study were to anaylize the influence of family strength on pregnancy quality. The data were analyzed from the study of "Effect of multinutrient fortified food suplement on pregnancy outcomes", which had been done previously by the Departement of Community Nutrition and Family Resources of IPB. Some additional information on family strength was also collected retrospectively. Of the 615 pregnant mothers in Luwiliang district (19 villages) and Cibungbulang district (15 villages), 233 mothers met the sample criterias were selected Pregnancy quality was measured by pregnancy weight gain. Family strength data (q=0.7) consisted of informations on physical resources, non-physical resources. Family problems, capping mechanism, physical well-being, social well-being, and psychologycal well-being. Applying a multiple linear regression model, body weight at the beginning of pregnancy and family strength has a significant effect on pregnancy weight gain. The items of Family strength are health factor, family goal, free from anger, and social support. The above results implied that, increasing family strength should he the important factor in pregnancy quality.
The Influencing Factors to The Self Relience of Food Crops Farmers in Their Agribusiness in Kampar District, Riau Province ., Marliati; ., Sumardjo; Asngari, Pang S.; Tjitropranoto, Prabowo; Saefuddin, Asep
Forum Pasca Sarjana Vol 33, No 3 (2010): Forum Pascasarjana
Publisher : Forum Pasca Sarjana

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The sustainable productivity of farmers can be realized if farmers own self relience. Farmers’s self relience can be realized if farmers own capacity to optimize self capacity and utilization of agriculture resources capacity.  Through multistage cluster sampling technique, found 75 person as farmer’s sample. Research  data including primary data and secondary data. Analysis of data done  with correlation test, regression test and path analysis.  The conclusion of this research is the self reliance level in agribusiness of food crop farmers, including the category low.  The low level of self reliance of farmers in agribusiness caused by (a) the low level of capacity development needs of farmers in agribusiness, which include low development needs: productivity capacity; marketing capacity; capacity of the security business/agribusiness; capacity in group management; networking capacity and the capacity in performance improvement/progress; (b) low level of performance of agricultural extension; (c) low levels of non-formal education of farmers.   Key words: agriculture extension worker, empowerment, capacity development, self-reliance, agribusiness
ANALISIS DERET WAKTU DENGAN RAGAM GALAT HETEROGEN DAN ASIMETRIK Studi Indeks Harga Saham Gabungan (IHSG) Periode 1999-2008 Untari, Nirawita; Mattjik, Ahmad Ansori; Saefuddin, Asep
FORUM STATISTIKA DAN KOMPUTASI Vol 14, No 1 (2009)
Publisher : FORUM STATISTIKA DAN KOMPUTASI

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Indeks Harga Saham Gabungan (IHSG) merupakan salah satu indikator yang digunakan pemerintah dalam mengambil kebijakan dalam bidang ekonomi. Selain itu pemerintah menganggap pentingnya pasar modal sebagai alternatif pembiayaan selain perbankan. Fluktuasi yang sangat besar terjadi di pasar bursa, karena setiap transaksi tercatat dengan skala waktu yang kecil sehingga perubahan nilai yang terjadi begitu cepat. Pada kasus ini asumsi kehomogenan ragam tidak terpenuhi. Pada pasar bursa juga memperlihatkan adanya pengaruh asimetrik(leverage), yaitu hubungan yang negatif antara perubahan nilai return dengan pergerakan volatilitasnya. Model EGARCH yang memodelkan ragam bersyarat sebagai fungsi log-linear digunakan sebagai fungsi ragam dalam memodelkan nilai harian IHSG, sehingga nilai ragam bersyarat yang diprediksi tidak akan pernah negatif. Model EGARCH terpilih adalah MA(1)-EGARCH(1,1). Model EGARCH terbukti sangat baik dalam memodelkan nilai harian IHSG, tetapi belum cukup baik untuk meramalkan nilai IHSG yang akan datang. Selain ramalan terhadap nilai harian IHSG, pemodelan fungsi ragam juga menghasilkan peramalan terhadap ragam bersyaratnya. Ramalan ragam bersyarat sangat berguna bagi pemegang aset dalam melihat perilaku pergerakan IHSG dan untuk menghitung besarnya resiko memegang suatu aset di masa yang akan datang.
PERFORMANCE COMPARISON BETWEEN KIMURA 2-PARAMETERS AND JUKES-CANTOR MODEL IN CONSTRUCTING PHYLOGENETIC TREE OF NEIGHBOUR JOINING Prasetya, Hendra; Saefuddin, Asep; ., Muladno
FORUM STATISTIKA DAN KOMPUTASI Vol 16, No 1 (2011)
Publisher : FORUM STATISTIKA DAN KOMPUTASI

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Bioinformatics as a recent improvement of knowledge has made an interest for scientist to collect and analyze data to provide the best estimate of the true phylogeny. The objective of this research is to construct and compare the phylogenetic tree of Neighbour Joining (NJ) based on different models (Kimura 2-Parameters and Jukes-Cantor) and to find out which model is more reliable on constructing NJ´s tree. In order to build the tree, reliable set of data is conducted from D-loop mtDNA sequences that is available in Gen Bank. The nucleotide sequences come from Bison bison (American bison), Bos taurus (European cow such as Shorthorn), Bos indicus (zebu breeds), Bos grunniens mutus (one of subspecies of cow), and Capra hircus (species of goat). The reliability of each models was measured using the Felsentein´s bootstrap method. The whole bootstrap process for each models was repeated 1.000, 5.000, and 10.000 times to detect its reliability. The performance was measured on the basis of the consistency of the topology relationship, the stability of nodes, the consistency of bootstrap confidence level (PB), standard error of distance, change of PB from (1.000-5.000) to (5.000-1.000), computational time, and  BIC score. NJ´s phylogenetic tree with kimura 2-parameters and jukes cantor model have a good node stability and is also generally successful in representing topological relationships between taxa. The increasing of bootstrap replication number in common will increase the consistency of bootstrap confidence value ( . It means both models have a good reliability. But, when the number of sequences is large and the extent of sequence divergence is low, it is generally difficult to construct the tree by any models. In conclusion, Kimura 2-Parameters has a better performance than Jukes-Cantor.   Key words: phylogenetic tree, Neighbour Joining, Kimura 2-Parameters, Jukes-Cantor
Penerapan Metode Mivque dalam Pendugaan Sifat Genetik pada Produksi Susu Sapi Saefuddin, Asep; Kurnia, Anang; Jaya, Citra
FORUM STATISTIKA DAN KOMPUTASI Vol 8, No 2 (2003)
Publisher : FORUM STATISTIKA DAN KOMPUTASI

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Ada beberapa ha1 yang mempengaruhi keragaman produksi susu sapi. Secara garis besar,dapat dibagi ke kdam dua kelompok yaitu faktor genetik dun faktor lingkungan. Keragamangenetik yang tinggi pada produksi susu. sari mcnunjukkan lingkungan tidak terlalu berpei~garuhterhadak produksi. Dalam dunia nyata, keragaman yang sebenarnya tidak mungkin diketahui,sehingga diprlukan pendekatan metode statistika dalam pendugaannya. Analisis statistika yangsering dipergunakan dalam menganalisis hubungan antar fakfor respon dengan faktorpenjelasnya adalah analisis model linier. Akan tetapi, analisis ini dibatasi asumsi bahwa faktorfaktoryang terlibat bersifat tetap (fixed), sehingga diperlukan pendekatan lain jika melibatkanfaktor yang bersifat acak. Analisis linear mixed model rnenyediakan fasilitas untuk menganalisisfaktor tetap maupun acak, dengan fokus utamanya adalah mengenai ragam komponen acak. Hasilpenelitian ini menunjukkan bahwa satu-satunya faktor tetap yang nyata pada taraf 0.05 ada;ahfaktor laktasi. Struktur koragam yang paling baik memodelkan faktor acak berdasarkan nilai AICadalah Unstructured Covariance. Sedangkan untuk pendugaan keragaman genetik, jenis Varlourmenjadi jenis pejantan yang paling superior dilihat dari nilai harapan kemajuan genetik dunkontribusinya terhadap keragaman produksi susu anaknya.Kata kunci : Sifat genetik, Linear Mixed Model
Measurement of Family Strength Sunarti, Euis; Syarief, Hidayat; Megawangi, Ratna; ., Hardiansyah; Saefuddin, Asep; ., Husaini
Media Gizi dan Keluarga Vol 27, No 1 (2003): Media Gizi dan Keluarga
Publisher : Media Gizi dan Keluarga

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Based on the family theory of structural functionalism, family is the first and the main porosity of human resource development. Family is the basic unit of society. The objectives of this study were to develop a measurement of family strength with high reliability and validity and to formulate policy implications to increase the family strength. 233 families from Leuwiliang district (19 villages) and Cibungbulang district (15 villages) were analyzed. Family strength data consisted of informations on physical resources, non-physical resources, family problems, copping mechanism, physical well-being, social welll-being, and psychological well-being. Applying Alpha Cronbach analysis, the family strength measurement had internal consistency coeficient of reliability 0.7 and applying factor analysis and Lisrel (Linear Structural Relationship) shared that there were there major latent variables of family strength, viz physical, social, and psychological. Strengthening the family should be an entegrated part of social economic, and family funcitioning development.
Co-Authors . Marzuki . Sutriyati ., MARTINA ACHMAD . Ahmad A. Mattjik Ahmad Ansori Mattjik Aji H. Wigena Aji Hamim Wigena Alinda FM Zain Ananda, Frisca Rizki Anang Kurnia Anggana, Hilman Dwi Ani Suryani Anik Djuraidah Arief Daryanto Arman Arman Arnita Arnita Bagus Sartono Bambang Indriyanto, Bambang Basita Ginting Budi Marwoto Bunasor Sanim Cece Sumantri CECEP KUSMANA Chalid Talib Citra Jaya DAMAYANTI BUCHORI Daowen Zhang Dewi Juliah Ratnaningsih Dewi, Lia Ratih Kusuma Diah Krisnatuti Dian Handayani Dian Kusumaningrum Dian Kusumaningrum, Dudung Darusman Eka Intan Kumala Putri Enny Kristiani Etih Sudarnika Etty Riani Euis Sunarti H. R. Eddie Gurnadi HAJRIAL ASWIDINNOOR Harahap, Tagor Alamsyah Harapin Hafid H. Hardiansyah . Hardinsyah . Hardinsyah Hardinsyah Hari Wijayanto Hartoyo, harry Hendra Prasetya Herlina, Marizsa HERMANTO SIREGAR Hidayat Syarief Husaini . I Made Sumertajaya I Wayan Mangku Jajang Jajang Jodi Vanden Eng Joko Sutrisno Khairil A. Notodiputro Khairil Notodiputro Anwar Notodiputro Lia Budimulyati Salman, Lia Budimulyati Lilik Noor Yuliati MANGARA TAMBUNAN Margono Slamet Marliati . Marliati Marliati MIRNAWATI SUDARWANTO Muladno . Ninuk Purnaningsih Nirawita Untari Nunung Nuryartono Nurul Hidayati Nusar Hajarisman Pang S. Asngari Pien Budiyanto, Pien Prabowo Tjitropranoto Pradina, Fathia Anggriani Priyadi Kardono Purmalino, Andres Purnomohadi, Eri Putri, Sarah R. Ruswandi Ratna Megawangi Rimun Wibowo, Rimun Rita Kusriastuti Ronny Rachman Noor Rudy Priyanto S. Damanhur, Didin Santun R.P. Sitorus Sarsidi Sastrosumarjo Setiadi Djohar Setiawan Setiawan Siti Sundari Sjafri Mangkuprawira Soedijanto Padmowihardjo Soekirman Soekirman Soetrisno Hadi Sony Sunaryo Suhartono, Doni Sulaiman, Fatah Sumardjo . Sumardjo Sumardjo Sumarjo Gatot Irianto, Sumarjo Gatot Sumartono Sumartono Sutarman . Syafri Mangkuprawira Syarifah Iis Aisyah Tamonob, Arista Marlince Tati Rajati triguna, gunadi Ujang Sumarwan Umi Cahyaningsih Upik Kesumawati Hadi William A. Hawley Yani Nurhadryani Yekti Widyaningsih Yenni Angraini Yulita, Tiyas Yuni Ros Bangun Yusuf, Eva Z Zinggara hidayat