Judul: Analisis Regresi Menggunakan Metode Kuantil
Abstrak: Regression analysis is applied to analyze relation between response variable with one or more predictor variable, especially to construct a model that has not been known. In order to estimate the regression parameters, certain estimation method of regression coefficients are carried out. In this paper quantile regression method is applied to asymmetric data. This method divides data into two or more groups, where existence of different estimated values at different quantiles are suspected. In this regression analysis, the regression coefficients are estimated using quantiles regression approximation properties, i.e. weighted least square approximation with all predictor variables included and the suites approximation with partial regression decomposition for certain predictor variables. Quantile regression approximation property explains that the quantile regression coefficient vector can minimize the expected value of weighted mean square error, which will give the best fit. The quantile regression with suites approximation is used to omit predictor variables which do not have influence to the model. The approximation properties of quantile regression are illustrated with the salary data from the U.S. census at 1980, 1990, and 2000. Key word: quantiles regression, asymmetric data, weighted least square, partial regression.
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Judul: Perbandingan metode regresi kuadrat terkecil dengan metode kekar
Abstrak: Ordinary least squares method is generally used to estimate parameter of a linear model. However, ordinary least squares is vulnerable against outliers because this method treats every element of data with equal weight. To overcome this problem, several studies have been done to find methods that produce more robust estimator. The robust methods being studied in this paper are weighted least squares, least absolute deviations, least median squares, and least trimmed squares methods. The comparison among those methods indicates that the method of least absolute deviation and weighted least squares are more resistant in case of the presence of outliers in the dependent variable. Meanwhile, least median squares and least trimmed squares methods are resistant to the presence of outliers both in the dependent and independent variable.
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Judul: Budidaya Bunga Potong Tulip (Tulipa gesneriana L.) dan Matthiola (Matthiola incana L.) di Perusahaan Firma Bosdijk, Nieuwe Wetering, Belanda Selatan.
Abstrak: Bunga potong merupakan komoditas dengan jumlah ekspor tertinggi di Belanda yang mencapai nilai ekspor sebesar 9.1 juta euro. Magang dilaksanakan di Perusahaan Firma Bosdijk, Nieuwe Wetering, Belanda Selatan dari 19 Februari sampai 19 Mei 2018. Magang ini bertujuan untuk meningkatkan keterampilan dan pengetahuan dalam aspek budidaya bunga potong tulip dan Matthiola dan aspek khusus berupa pertumbuhan dan produksi tulip, serta pengaruh cahaya LED terhadap pertumbuhan bunga potong Matthiola. Pelaksanaan magang dilaksanakan dengan mengikuti semua kegiatan budidaya tulip dan Matthiola mulai dari penanaman hingga pengemasan. Budidaya serta pengelolaan panen dan pascapanen bunga potong tulip dan Matthiola sudah dilakukan dengan menggunakan mekanisasi yang tinggi dengan persentase panen bunga tulip yaitu sebesar ≥ 80% dari total populasi. Penurunan produksi tulip pada tahun 2018 terjadi karena ukuran umbi yang lebih besar, dan jumlah varietas yang ditanam lebih sedikit. Tulip varietas Versaci memiliki harga jual yang lebih tinggi karena morfologinya yang unik dengan warna tepalnya merah dan terdapat serabut di bagian ujung tepal. Pemberian cahaya LED dapat meningkatkan tinggi tanaman dan jumlah daun bunga Matthiola varietas Matthilda pink. Pemberian cahaya LED dapat meningkatkan diameter bunga varietas Figaro lavender dan Aida white, dan meningkatkan panjang bunga varietas Figaro Lavender dan Matthilda pink. Pemberian cahaya LED juga mampu mempercepat 1-2 minggu umur panen Matthiola untuk seluruh varietas yang diamati.
Keyword: cahaya LED, karakter morfologi, Matthilda Pink, Versaci