Judul: Content Analysis of Consumer Reviews and Comments on E-commerce in Indonesia
Abstrak: Online consumer review (OCR) merupakan salah satu bentuk E-WOM yang dapat menjadi sumber informasi dan sumber acuan bagi calon konsumen dalam mengambil keputusan. Penelitian ini bertujuan untuk menganalisis isi review dan komentar konsumen pada e-commerce di Indonesia. Penelitian ini menggunakan desain penelitian mix method. Penelitian kuantitatif dilakukan dengan teknik survei menggunakan instrumen kuesioner. Penelitian kualitatif dilakukan dengan teknik analisis isi dan indepth interview. Analisis isi dilakukan dengan mengamati review dan rating yang diberikan konsumen pada produk fashion di toko online yang berada di e-commerce Shopee dan Tokopedia. Indepth interview dilakukan kepada dua konsumen dan satu penjual. Pengolahan dan analisis data dilakukan dengan menggunakan aplikasi Microsoft Excel, dan Statistical Package for Social Science (SPSS) 25.0. Data yang diperoleh dalam bentuk komentar dilakukan analisis sentimen. Hasil dari penelitian ini menunjukkan bahwa hampir semua konsumen melihat rating dan review sebelum membeli produk fashion. Kebanyakan konsumen hanya memberikan rating tanpa disertai dengan review. Hasil penelitian juga menunjukkan bahwa ulasan mengenai kualitas produk, dan ulasan mengenai harga merupakan ulasan paling banyak dibahas oleh konsumen yang membeli produk fashion. Terdapat konsumen yang memberikan komentar yang tidak sesuai, menggunakan kata-kata berulang atau kata-kata yang dipanjangkan hurufnya., Online consumer review (OCR) is a form of E-WOM that can be a source of information and a source of reference for potential consumers in making decisions. This study aims to analyze the content of consumer reviews and comments on e-commerce in Indonesia. This study uses a mixed method research design. Quantitative research is carried out by survey techniques using a questionnaire instrument. Qualitative research was conducted using content analysis techniques and in-depth interviews. Content analysis is carried out by observing reviews and ratings given by consumers on fashion products in online stores in the e-commerce Shopee and Tokopedia. In-depth interviews were conducted with two consumers and one seller. Data processing and analysis was performed using Microsoft Excel application, and Statistical Package for Social Science (SPSS) 25.0. The data obtained in the form of comments is subjected to a sentiment analysis. The results of this study indicate that almost all consumers look at ratings and reviews before buying fashion products. Most consumers only give ratings without being accompanied by a review. The results also show that reviews about product quality and reviews about prices are the most discussed reviews by consumers who buy fashion products. There are consumers who give inappropriate comments, use repetitive words or words that are lettered out.
Keyword: content analysis, e-commerce, online consumer rating, online consumer review, online shopping

Judul: Credibility of Online Consumers Reviews of Health Products on Two E-commerce in Indonesia: Mixed Methods Approaches
Abstrak: Banyaknya ulasan yang disampaikan konsumen telah menyebabkan kelebihan informasi, sehingga konsumen kesulitan mencari ulasan yang kredibel. Penelitian ini bertujuan untuk mengidentifikasi karakteristik konsumen, karakteristik ulasan dan perilaku berbelanja online, mengklasifikasikan kelas sentimen, dan menganalisis kredibilitas ulasan konsumen. Pada penelitian ini, digunakan desain penelitian Mixed Methods melalui Concurrent Embedded Strategy. Selanjutnya, data diolah dan dianalisis menggunakan aplikasi Statistical Package for Social Science (SPSS) 25.0 dan software Nvivo 12 Plus. Hasil penelitian menunjukkan bahwa konsumen yang sering membeli produk kesehatan secara online pada masa pandemi COVID-19 didominasi oleh generasi Z, ulasan online dijadikan sumber informasi utama untuk menentukan keputusan pembelian. Kelas sentimen negatif pada ulasan, dapat dijadikan bahan evaluasi bagi penjual. Hasil analisis, pada aspek source credibility dan recommendation rating, ulasan yang disampaikan konsumen masih didominasi oleh ulasan yang tidak kredibel, sedangkan pada aspek e-WOM quality, umumnya ulasan yang disampaikan konsumen sudah menggunakan foto dan/atau video sesuai dengan produk yang dibeli, rating sudah sesuai dengan ulasan yang disampaikan dan bahasa dapat dipahami., The large number of reviews submitted by consumers has led to information overload, making it difficult for consumers to find credible reviews. This study aims to identify consumer characteristics, online shopping behavior and consumer reviews, classify sentiment classes and analyze the credibility of consumer reviews. In this study, a Mixed-Methods research design was used through a Concurrent Embedded Strategy. Furthermore, the data are processed using the SPSS 25.0 and the Nvivo 12 Plus software. The results showed that the Z generation dominated consumers who often bought health products online during the COVID-19 pandemic. Online reviews were used as the primary source of information in the information search process to determine purchase decisions. The negative sentiment class on the review can be used as an evaluation material for the seller. Furthermore, the analysis results show that in the aspect of source credibility, reviews submitted by consumers are still dominated by reviews that do not use the original name or photo of the reviewer. In the e-WOM quality aspect, generally, consumers' reviews have used photos and/or videos according to the product purchased. The rating is in accordance with the review submitted and the language can be understood. In addition, on the recommendation rating aspect, almost all of them are still dominated by reviews that have not been responded to by other consumers.
Keyword: content analysis, the credibility of review, e-commerce, online consumer reviews, sentiment analysis

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model