Aunuddin .
Departemen Statistika FMIPA – IPB

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KAJIAN SIMULASI KETAKNORMALAN PENGARUH ACAK DAN BANYAKNYA DERET DATA LONGITUDINAL DALAM PEMODELAN BERSAMA (JOINT MODELING) (Simulation Study of Random Effects Nonnormality and Number of Longitudinal Data Series in Joint Modeling) Indahwati .; Aunuddin .; Khairil Anwar Notodiputro; I Gusti Putu Purnaba
FORUM STATISTIKA DAN KOMPUTASI Vol. 16 No. 2 (2011)
Publisher : FORUM STATISTIKA DAN KOMPUTASI

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Abstract

Joint modeling is intended to model longitudinal response process that affect the other primary response based on  assumption that both  processes induced by the same random effects. One of the assumptions that must be met in joint modeling is  normality  of  random  effects  and  intra-subject  error.  The  simulation  results show that the robustness of parameter estimates of joint model to the assumption of  random  effects  normality  can  be  achieved  by  increasing  the  frequency  of longitudinal observations.  Keywords:  longitudinal data,  joint modeling, robust
GENERALIZED VARIANCE FUNCTIONS FOR BINOMIAL VARIABLES IN STRATIFIED TWO-STAGE SAMPLING Ari Handayani; Aunuddin .; Indahwati .
FORUM STATISTIKA DAN KOMPUTASI Vol. 10 No. 1 (2005)
Publisher : FORUM STATISTIKA DAN KOMPUTASI

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Abstract

      This empirical study evaluates the application of Generalized Variance Functions (GVFs) for binomial variables in the 1998 Indonesian Labor Force Survey. The survey employs stratified two-stage cluster sampling for selecting samples from a population of households. The study covers all provinces in Java to produce estimates at the level of Java Island. The relative variance estimates resulted from the GVF models are compared to the relative variance estimates which are computed directly. The results illustrate that  model  expressed by logarithmic model  log = log c + d log () gives a good approximation to estimate the variances for the nonagricultural employment group, especially for working male category both in urban and rural areas. It is also good for the total employment group differentiated by age group, educational attainment, and employment status. On the other hand, the model gives poor results for the agricultural employment group. Based on the empirical results, the GVF models may not perform particularly well for the common characteristics which have relatively dissimilar deff values to majority of characteristics in the same group, since these characteristics usually come out among all persons in the sample household and often among all households in the sample cluster as well. The success of the GVF technique depends critically on the grouping of the estimates total () and amount of characteristics involved as the observations for fitting the model. Furthermore, observations with relatively large residuals will also determine the performance of goodness-of-fit of the model. Application of GVF technique to obtain an approximate standard error on numerous binomial characteristics in large scale survey should be carried out further using extensive data. The better performance of GVF model may also be accomplished by utilizing, for examples, weighted least squares procedure or robust regression method. Additionally, the data users should be warned that there will inevitably be survey characteristics for which GVF's will give poor results or even no GVF will be appropriate. Keywords :  Generalized Variance Functions, Stratified Two-Stage Sampling
PENELUSURAN NILAI KORELASI PADA PROSES PRODUKSI TEPUNG BAKU SEMEN Aunuddin .; Erfiani .; Nenden Rahayu Puspitasari
FORUM STATISTIKA DAN KOMPUTASI Vol. 10 No. 1 (2005)
Publisher : FORUM STATISTIKA DAN KOMPUTASI

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Abstract

Penelitian mengenai pengendalian mutu terhadap proses produksi tepung baku semen telah dilakukan sebelumnya. Penelitian tersebut menyimpulkan bahwa proses produksi tidak terkendali karena adanya perpindahan blok pada saat penambangan bahan baku semen (Puspitasari 2005). Selain itu, penelitian tersebut juga menyebutkan bahwa nilai korelasi antar karakteristik mutunya terlalu kecil sehingga selain penggunaan bagan kendali peubah ganda, penggunaan bagan kendali peubah tunggal juga n bagan kendali peubah ganda  proses tidak terkendali pada data awal i peubah tunggal bisa digunakan pada penelitian ytersebisa digunakan pada penelitian tersebut. Dalam tulisan ini akan dilihat lebih lanjut mengenai struktur korelasi yang terjadi antar karakteristik mutunya. Hasil penelusuran nilai korelasi antar karakteristik mutu pada kondisi awal, kondisi proses tidak terkendali dan kondisi proses terkendali menunjukkan adanya perubahan jika dibandingkan satu sama lainnya. Namun besarnya perubahan nilai tersebut relatif kecil, dan jika dilihat dari kedekatannya dapat dikatakan bahwa nilai korelasi pada saat kondisi proses terkendali lebih dekat dengan nilai korelasi pada saat kondisi proses tidak terkendali   Kata kunci: Korelasi, Tepung baku semen, Karakteristik mutu