Penaksir untuk Rasio Populasi dengan Menggunakan Koefisien Regresi dan Dual pada Variabel Tambahan

In this article we discuss three estimators for population ratio using the coefficien regression and dual, which is a review from the article of Onyeka et.al [GlobalJournal of Science Frontier Research, 13(2013):57-65]. The three estimators are biased estimators and their mean square errorsare determined. Furthermore, this mean square errorsare compared to mean square error of each estimator.This comparison shows that thetype-product estimator is more efficient than another estimators

Penaksir Rasio dan Penaksir Regresi yang Efisien untuk Rata-rata Populasi pada Sampling Acak Sederhana Menggunakan Deviasi Kuartil dan Koefisien Skewness

In this article the combination of ratio estimators and ratio-regression in simple random sampling using quartile deviation and coefficient of skewness are discussed, which is a review from the article Jeelani et.al. [International Journal of Modern Mathematical Sciences, 6(3): 174-183]. These estimators are biased estimators and their mean square errors are determined. Estimator with the smallest mean square error is the most efficient estimator. A numerical example is given at the end of discussion

Perbandingan Model Pemulusan Winter Dengan Arma(p, Q) Untuk Peramalan Stok Beras Bulog Pekanbaru

This article discusses Winter's smoothing and ARMA(p, q) model through numerical computation. Both of these models are used to predict the availability of rice stocks at National Logistics Agency or BULOG in Pekanbaru City by considering the seasonal factor from time series span data. Then a comparison iscarried out for both forecasting models to select the right forecasting model using minimum mean square error