Judul: Regresi binomial negatif dan zero inflated poisson peubah yang berpengaruh terhadap dropout (DO) mahasiswa S2 pascasarjana IPB
Abstrak: Peminat program pascasarjana dari tahun ke tahun mengalami peningkatan, ini membuat banyak perguruan tinggi membuka program pascasarjana. Salah satu perguruan tinggi yang membuka program pascasarjana adalah Institut Pertanian Bogor (IPB). Tingginya peminat program pascasarjana tidak membuat semua mahasiswanya dapat menyelesaikan pendidikan pascasarjana sampai akhir, sehingga mereka harus mengalami dropout. Kasus dropout ini dipengaruhi banyak faktor, adapun faktor-faktor yang diduga berpengaruh yaitu jenis kelamin, usia mahasiswa, status pernikahan, status pekerjaan, status PT asal, IPK S1, sumber biaya pendidikan, dan linearitas S1. Metode yang dapat digunakan untuk melihat faktor yang berpengaruh adalah regresi binomial negatif dan regresi zero inflated poisson. Regresi zero inflated poisson memiliki dua model yaitu model log dan model logit. Data yang digunakan merupakan data dropout mahasiswa pascasarjana IPB dari tahun 2005 sampai dengan tahun 2013. Regresi binomial negatif memiliki nilai AIC sebesar 351.9181, sedangkan regresi zero inflated poisson memiliki nilai AIC sebesar 256.3708. Sehingga pada kasus dropout pascasarjana IPB regresi yang paling baik digunakan adalah regresi zero inflated poisson karena menghasilkan nilai AIC yang lebih kecil dari regresi binomial negatif. Peubah yang berpengaruh terhadap dropout mahasiswa pascasarjana menggunakan regresi zero inflated poisson dengan model log adalah rata-rata usia mahasiswa, persentase mahasiswa menikah, persentase mahasiswa bekerja, persentase status PTN asal mahasiswa, rata-rata IPK S1, dan persentase daerah PT asal luar pulau Jawa, sedangkan jika menggunakan model logit tidak ada peubah yang berpengaruh.
Keyword: AIC, IPB, Negative binomial regression, Zero inflated poisson regression, Perbandingan regresi binomial, Ukuran kebaikan model, Kaus drop out

Judul: Factors identification of stop study ipb graduate students using logistic regression and zero inflated poisson
Abstrak: Bogor Institute of Agriculture (IPB) make every effort to increase quality of graduates and percentage of students passing rate. Quality of graduates can be viewed based on the value of GPA and graduation time. Passing rate can be calculated from the ratio of the number of graduates to the number of students in one class. Students stopped the study is one issue that is still a concern because can harm their own students, institutions, and the country. In this research will examine the factors that affect graduate students IPB stop study. The first study in terms of the status of the students stop studies using logistic regression. The second study in terms of the number of occurences of students who stopped the study in each course using Poisson regression. Poisson regression model on the discrete data of the type that sometimes occurs overdispersi value greater variety from the average value. In general, the model can be used for data overdispersi is a zero inflated Poisson regression. The data used in this research were graduate students of data generation IPB 2005- 2010. Based on the results of logistic regression analysis states that male student has the opportunity to stop the study was higher than women, the graduate students coming from PTS have the opportunity to stop the study is higher than those from PTN, students with tuition fee independent source has the opportunity to stop the study was higher than the students receiving scholarship and students are not linear S1 has a chance to stop the study was higher than that of linear S1. Evaluation study conducted by program of study by using zero inflated Poisson regression to model the log shows that the smaller the percentage of married students, an average GPA of S1, and the greater the percentage of students receiving scholarships will increase the number of graduate students who stop his studies while IPB. Logit models showed IPB graduate students opportunities stop study is influenced by the percentage of male students, the percentage of married students, the percentage of college country of origin, and the percentage of scholarship recipients.
Keyword: stop study, logistic regression, zero inflated poisson regression

Judul: Characterizations of low alloy steel sae 4422  plated with chromic acid (Cro3)
Abstrak: Characterizations of low alloy steel SAE 4422 plated with chromic acid (CrOrO3) was use Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), RD),Energy Dispersive Analysis of X-Ray (EDAX), Hardness Test and Roughness Test. Microstructures analysis exhibits cracks and grain boundaries microcracks as a characteristics of chrome metal found at plating metal. Perlite and Ferrite as grains of steel found at base metal with grain boundaries around it. Phase analysis of plating metal appropriate to chrome metal with lattice constant (a) is 2.559 Å and phase analysis of base metal appropriate to iron ferrite with lattice constant (a) is 3.318 Å. Both plating and base metal have cubic system. Chemical analysis of plating metal at surface section exhibits that cracks area have highest value of carbon element compare with grains and grains boundaries area. While chemical analysis of base metal at cross section exhibits that perlite have highest value of carbon element compare with ferrite and grain boundaries. The hardness value of plating metal at surface section and cross section are 753 and 637 VHN. While, the hardness value of base metal and interface area at cross section are 205 and 373 VHN. The roughness value at measurement points of chrome surface for as received sample are 0.445 μm. Observation used Optical Microscopy and Scanning Electron Microscopy exhibits surface irregularities combine to form surface texture of plating metal at surface section.
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