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: Kajian Pemodelan Regresi Kekar Menggunakan Metode Penduga-MM dan Kuadrat Median Terkecil
Abstrak: Regresi merupakan metode statistika yang digunakan untuk menduga pola hubungan dua peubah atau lebih yang disajikan dalam persamaan garis regresi. Persamaan garis ini umumnya diperoleh dari pendugaan menggunakan metode kuadrat terkecil (MKT). Namun demikian, MKT memiliki keterbatasan yaitu sangat dipengaruhi pencilan. Salah satu penyelesaian masalah pencilan pada analisis regresi adalah menggunakan metode regresi kekar. Penelitian ini menggunakan regresi kekar median kuadrat terkecil atau LMS dan multi-stage method (MM). Analisis dilakukan terhadap data simulasi hasil pembangkitan dan data aktual. Simulasi analisis regresi menghasilkan kesimpulan bahwa metode LMS maupun MM memiliki kinerja lebih baik dibandingkan dengan MKT pada data yang mengandung pencilan. Metode MM memiliki rata-rata nilai bias pendugaan parameter terkecil, diikuti oleh LMS kemudian MKT. Metode LMS memiliki ratarata nilai root mean squares error (RMSE) terkecil dan rata-rata 𝑅������2 tertinggi, diikuti oleh MM kemudian MKT. Hasil perbandingan analisis regresi ketiga metode tersebut pada data produksi padi Indonesia tahun 2017 yang mengandung 10% pencilan diperoleh kesimpulan bahwa metode LMS merupakan metode terbaik. Metode LMS menghasilkan RMSE terkecil yaitu sebesar 4.44 dan 𝑅������2 tertinggi yaitu sebesar 98%. Metode MM berada pada posisi kedua terbaik dengan RMSE 6.78 dan 𝑅������2 96%. MKT menghasilkan RMSE terbesar dan 𝑅������2 terendah yaitu berturut-turut sebesar 23.15 dan 58%.
Keyword: least median of squares,, encilan, regresi kekar, root mean squares error

Judul: Co-infection of Infectious Myonecrosis Virus (IMNV) and Vibrio harveyi in Pacific White Shrimp (Litopenaeus vannamei)
Abstrak: L. vannamei production in Indonesia was growing intensively. In 2006, IMN (infectious myonecrosis) disease was confirmed spread to Indonesia shrimp farm and declined shrimp production. The study was conducted to investigate effect of dose of V. harveyi on co-infection with IMNV in L. vannamei as well as development of viral infection. Shrimps juvenile were oral infected with IMNV infected shrimps 10 % feeding rate during 3 days and co-infected with 106, 107 and 108 cfu/ml V. harveyi. Mortality rate was 0 % in control and single infection of V. harveyi except 108 cfu/ml treatment. Mortality pattern demonstrated on co-infection was faster and higher than single IMNV infection in 14 days observation. The density of green colony Vibrio in hepatopancreas of co-infected shrimps collected in 2, 4, 6, 8 and 10 days post infection were higher than V. harveyi single infected (significantly in 10 days post infection). There were no difference of IMN disease development between co-infection and IMNV single infection. It was confirmed by visual gross sign appeared, tissue and lymphoid organ histophatology, organ abnormality, and PCR test. In conclusion, IMN disease caused higher and faster mortality on co-infection with V. harveyi, but not affect to IMN disease development.
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