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: Kajian metode pendugaan pada model regresi dengan peubah penjelas bersifat acak
Abstrak: Regression analysis is a statistical method to evaluate the relationship between a variable with other variables. Model I regression analysis describes the one-way relationship between variable X and variable Y with the value of X as fixed variable or measured without error. Model I regression analysis uses Ordinary Least Square (OLS) as an estimation method. Model II regression analysis is a regression model with predictors variable that becomes a random variable. There are two estimation methods of model II regression analysis, ordinary least product regression (Model IIA) and major axis regression (Model IIB). The convenience of using model I regression analysis with OLS estimation method causes many researchers to use this model as a model regression analysis with random predictor variables. The purpose of this study is to compare model I regression analysis (OLS estimation method) and model II regression analysis (ordinary least product estimation method and major axis regression estimation method). The data used in this research are simulation data where response variable (Y) and predictor variable (X) are random. The result of this study showed for predictor variable is random, ordinary least product regression is the best estimation method compared to the other methods because it produces the smallest value of bias and the smallest value of mean square error. In this condition, OLS can be used for the estimate parameter of simple linier regression model if the correlation value between predictor variable (X) and response variable (Y) is high (r ≥ 0.9).
Keyword: Bogor Agricultural University (IPB), Model IIB, Model IIA, Model I, mean square error, correlation

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