Judul: Penentuan Nilai Pembobotan dan Penduga Ragam Pada Penarikan Contoh Bertahap (Studi Kasus : Survei Pra Pemilihan Gubernur dan Wakil Gubernur Jawa Barat di Daerah Pemilihan Kota Bogor)
Abstrak: Sampling can be performed by using one or more stages. These stages are useful in order to obtain representative samples. It is often observed that parameters are estimated by assuming the samples are taken using simple random sampling (one stage) although they are taken using multistages which lead to invalid results. This study focus on estimation of parameters considering the stage in multistage sampling. As an illustration, we use pre-election survey of Governor and Vice Governor of West Java in Bogor City which involving three stages of selection, namely : (1) village within district, (2) neighborhood within village and (3) household within neighborhood. These stages are taken into account during estimation of number of voters in form of weights which are obtained by considering the selection process. It is obtained that the estimation using the weights are closer to the true number of voters released by KPU Bogor compared to the one not using the weights.
Keyword: Multistage Sampling, Estimation of Proportion, Weights and Variance of Estimators

Judul: Comparison of Sampling Techniques to Estimate Election Results (Case Study of Jembrana District Election, 2010)
Abstrak: The first local election held in Kutai Kartanegara on June 1, 2005. Among many quick count conducted, there are some different winner estimation with the results of Election Comission, especially in local elections where the candidates compete tightly. A research is required to improve the reliability of quick count methodology so it can be a reliable reference information for the public to estimate the election results. This research aims to get a sampling technique that is reliable by comparing several sampling techniques to estimate election result. A good survey design has high reliability and validity estimates (high prediction accuracy). The comparison of some sampling techniques showed that stratified random sampling (district and rural-urban status as strata) produce the best estimation considered from the realibility and estimation accuracy based on standard error and MSE. Techniques commonly used today (stratified random sampling by using systematic random sampling in choosing sample on each strata) have standard error and MSE slightly larger.
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Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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