Judul: Ketepatan dan ketelitian pendugaan parameter regresi linear model-II menggunakan MKT dan MKT ortogonal
Abstrak: Pendugaan parameter terhadap regresi linear model-II jika menggunakan MKT akan didapat nilai pendugaan yang selalu lebih kecil dari nilai sebenarnya. Sehingga akan mengakibatkan pendugaan yang berbias terhadap parameter tersebut. MKT dapat digunakan untuk menduga parameter regresi linear model-II jika nilai nisbah ragam galat (1) besar, karena nilai ragam galat peubah Y jauh lebih besar dari ragam peubah X. Jika nilai <1 maka pendugaan terhadap parameter regresi model-Il paling bagus menggunakan MKM, meskipun MKT Ortogonal juga tidak berbias tapi nilai KTG dari MKM lebih kecil dibandingkan MK.T Ortogonal. Sehingga MKM lebih teliti dibandingkan MKT Ortogonal. Jika > 1 maka MKT Ortogonal lebih bagus dibandingkan MKM, meskipun keduanya juga merupakan penduga yang tidak berbias. Sebab nilai KTG dari MKT Ortogonal selalu lebih kecil dari KTG MKM.
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Judul: Perbandingan Metode MKT, LTS, WIN, dan Theil pada Pendugaan Parameter Regresi Apabila Galatnya Menyebar Eksponensial
Abstrak: Parameter estimation in simple linear regression analysis can be done with Ordinary Least Square (OLS). This method requires the assumption that error must be Normally distributed. However, in reality error is not always Normally distributed, but has another distribution, for example Exponential. Concequently, parameter estimation by MKT is not optimal. This problem can be solved by applying robust regression. This research applied Least Trimmed Square (LTS) method, Winsorized Least Square (WIN) method, and Theil’s method as a solution. The data used in this study was simulation data. Explanatory variables (x) is generated from the Normal distribution, while the error generated from the Exponential distribution. The results of estimation are evaluated with MSE and Relative MSE. The results showed that LTS was the best method when the error is Exponentially distributed.
Keyword: Bogor Agricultural University (IPB), WIN, Theil’s Method, OLS, LTS

Judul: Lejeuneaceae Subfamily Ptychanthoideae (Hepaticae) in  West Java
Abstrak: Subfamily Ptychanthoideae of the family Lejeuneaceae (Hepaticae) in West Java is still poorly known. Publications on this subfamily are out of dated and written in the 19th or early of 20th century. The last taxonomic treatment of Ptychanthoideae of West Java was in 1933, many species names have changed since then. Studies on Ptychanthoideae of West Java are urgently needed. Studies on the Ptychanthoideae were based on the specimens collected from West Java. A total number of 361 of specimens deposited in the Herbarium Bogoriense (BO), Herbarium Biotrop (BIOT), Gottingen Herbarium (GOET) and Bangi Herbarium (UKMB) were examined, those are old and several recent specimens collected in West Java. Recent collections were made from Telaga Warna, Ciater, Gunung Halimun Salak National Park, Cibodas Botanical Garden, Bodogol Education Center and Conservation (Gunung Gede Pangrango National Park), University of Indonesia Campus Depok, including several collections from Banten Province. Twenty four species of Lejeuneaceae subfamily Ptychanthoideae are known from West Java, belonging to 8 genera namely Acrolejeunea (Spruce) Schiffn. (2 species), Archilejeunea (Spruce) Schiffn. (1 species), Lopholejeunea (Spruce) Schiffn. (10 species), Mastigolejeunea (Spruce) Schiffn. (3 species), Ptychanthus Nees (1 species), Schiffneriolejeunea Verd. (1 species), Spruceanthus Verd. (2 species) and Thysananthus Lindenb. (4 species). Two new records of Ptychanthoideae: Mastigolejeunea indica Steph. and Thysananthus minor Verdoorn are reported for Java. A determination key to the species is presented including their descriptions and illustrations.
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