Τμήμα Οικονομικών Επιστημών (ΔΕ)

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    Επίδραση ειδησεογραφίας στην τιμή των κρυπτονομισμάτων : μια εμπειρική προσέγγιση
    Γιούρτης, Κωνσταντίνος; Giourtis, Konstantinos
    In this dissertation we tried to examine if the news affect the price of cryptocurrencies. By saying news, we mean traditional news. Thus, we used articles from newspapers and for cryptocurrencies the closing price of Bitcoin. We collected the articles with the scraping method and our training and unknown data sets included 103 and 70 articles respectively. We used the Sentiment Analysis to extract the sentiment of each article. Also, to classify the unknown data set we used the Naive Bayes algorithm since we trained it with the training data set. In the following, since we got the sentiment results we estimated two regression models. The first one, was between the closing price of bitcoin and the sentiment of the articles and in the second model we added the variable of the website. The results show us that from the first model there is strong correlation between the bitcoin’s closing price and the sentiment at least in 5% level of significance. Especially, the positive articles increase the closing price compared to the negative articles. In addition, from the second model we concluded that when we add the variable of the website of each article, the variable of sentiment is not statistical significant but the variable of website is. Thus, the source of the article is more important rather that the article itself. Finally, we found strong correlation in both models with the time leads of the bitcoin’s closing price.
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    Open Access
    Gender aspects of unemployment dynamics in the Greek labour market
    Παπαχριστοπούλου, Μαρία; Γιαννακόπουλος, Νικόλαος; Τζελέπης, Δημήτριος; Τζαγκαράκης, Εμμανουήλ; Papachristopoulou, Mary
    In this dissertation, we investigate the relative contribution of the "ins" and "outs" of Greek unemployment, using micro-data from the Greek Labour Force Survey for the period 2004-2015. We proceed to an aggregate and a micro-level analysis, as well, in order to examine what drives unemployment fluctuations. We employ relevant decomposition techniques to explore unemployment dynamics at an aggregate level, using a three-state model of worker flows (employment, unemployment, inactivity). At the micro-level, data allow us to estimate quarterly transition probabilities across the main labour market statuses. We investigate the individual specific characteristics that determine transition probabilities using multinomial regression techniques. We especially focus on the changing role of factors that may affect labour market transitions in the presence of the Greek economic crisis.