Judul: Seleksi peubah dengan analisis komponen utama dan procrustes
Abstrak: Principal component analysis (PCA) is a dimension-reducing tool that replaces the variables in a multivariate dataset by a smaller number of derived variables. Dimension reduction is often undertaken to help in interpreting the data set but, as each principal component usually involves all the original variables, interpretation of a PCA can still be difficult. One way to overcome this difficulty is to select a subset of the original variables and use this subset to approximate the data. Procrustes analysis as a measure of similarity, is used to measure the efficiencies of the alternative variable selection methods in extracting representative variables Because of its unavailability in statistical software, a package program, using Mathematica 8.0, is composed for variable selection. There are four variable selection methods, based on PCA and procrustes analysis, which have been described and examined along with different criteria levels for deciding on the number of variables to retain in the analysis. The methods are B2, B4, procrustes analysis in the principal component score, and procrustes analysis method. The result show that variable selection programs B2 as the best variable selection method followed by procrustes analysis method. Moreover, it is found that all of the methods considered give the measure of efficiency of more than 99.04%.
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Judul: Penerapan Analisis Komponen Utama Kekar dengan Metode ROBPCA
Abstrak: Data dengan jumlah variabel dan observasi besar seringkali memerlukan penanganan khusus, baik dalam proses analisis maupun visualisasi. Proses analisis dan visualisasi ini bisa disederhanakan dengan cara reduksi dimensi menggunakan analisis komponen utama (AKU). Keberadaan pencilan akan sangat memengaruhi analisis suatu data sehingga diperlukan analisis dengan suatu pendekatan yang kekar (robust) terhadap pencilan. Salah satu pendekatan yang bisa digunakan adalah AKU kekar ROBPCA yang menggabungkan konsep projection pursuit dengan estimator Minimum Covariance Determinant. Suatu data contoh dianalisis menggunakan AKU klasik dan AKU kekar dengan metode ROBPCA. Berdasarkan plot tebaran score distance dan orthogonal distance, AKU ROBPCA efektif dalam mengidentifikasi pencilan dibandingkan dengan AKU klasik. Lebih jauh, hasil analisis biplot juga menunjukkan AKU ROBPCA lebih akurat dalam penanganan pencilan dibandingkan AKU klasik.
Keyword: kekar, analisis komponen utama, minimum covariance determinant, pencilan, projection pursuit

Judul: Durability of Specific Immunoglobulin (Ig) Y Againts Influenza and Covid-19 in Sunscreen
Abstrak: The benefit of specific immunoglobulin Y (Ig Y) as an active ingredient in personal care products such as sunscreen has not been properly studied. Our study aims to evaluate the reliability of specific IgY against influenza and the COVID-19 virus in a sample sunscreen product. Specific IgY influenza and COVID-19 viruses were inserted in the sample sunscreen at two concentrations of 0.1% and 0.25%. Three treatments were observed: control (C) sunscreen without IgY, treatment 1 (T1) sunscreen with 0.1% IgY, and treatment 2 (T2) sunscreen with 0.25% IgY. Organoleptic observations were carried out to monitor changes in aroma, color, and texture, and sunscreen sampling was done every week for 6 weeks. The durability of IgY was evaluated using an enzyme-linked immunosorbent assay (ELISA) and a neutralization assay. Organoleptic observation from weeks 1 to 6 showed consistency in its aroma, color, and texture. Enzyme-linked immunosorbent assay and neutralization assay (NA) results of the T1 and T2 groups showed negative results except for sample T1 at week 5, which showed a positive result in the Influenza A ELISA. Based on the results, it seems that IgY concentrations of 0.1% or 0.25% were not optimal. However, this negative result might be due to low concentration of the IgY and the presence of beeswax, which inhibits IgY and causes it to dissolve in distilled water, thus preventing it from being detected in the assay.
Keyword: Immunoglobulin Y, Sunscreen, Influenza, COVID-19, Biological Activity