474 research outputs found
Analyzing the Spread of Misinformation on Social Networks:A Process and Software Architecture for Detection and Analysis
The rapid dissemination of misinformation on social networks, particularly during public health crises like the COVID-19 pandemic, has become a significant concern. This study investigates the spread of misinformation on social network data using social network analysis (SNA) metrics, and more generally by using well known network science metrics. Moreover, we propose a process design that utilizes social network data from Twitter, to analyze the involvement of non-trusted accounts in spreading misinformation supported by a proof-of-concept prototype. The proposed prototype includes modules for data collection, data preprocessing, network creation, centrality calculation, community detection, and misinformation spreading analysis. We conducted an experimental study on a COVID-19-related Twitter dataset using the modules. The results demonstrate the effectiveness of our approach and process steps, and provides valuable insight into the application of network science metrics on social network data for analysing various influence-parameters in misinformation spreading.</p
Teorijsko-metodološki okvir analize rizika i prinosa na tržištu kapitala Srbije
APSTRAKT:
Dugi niz godina, brojni autori su nastojali da formulišu adekvatan model za
procenu rizika i prinosa hartija od vrednosti. Jedan od prvih takvih modela je
Model određivanja cene uloženog kapitala (Capital asset pricing model – CAPM), kod
koga je očekivana stopa prinosa hartije proporcionalna njenom sistematskom riziku
merenom beta koeficijentom. S obzirom na to da je CAPM model bio predmet brojnih
teorijskih rasprava, kao i empirijskog osporavanja, mnogi autori su se založili za
korišćenje alternativnih modela.
Predmet doktorske disertacije su alternativni modeli za procenu rizika i prinosa
na tržištu kapitala Srbije. Posebna pažnja je posvećena testiranju primenljivosti
bezuslovnog CAPM modela, CAPM modela sa betama negativnih odstupanja stopa
prinosa, modela sa merom rizika zasnovanom na poludevijaciji, uslovnog CAPM
modela u kojem bete i premije za tržišni rizik variraju u vremenu i modela sa
uključenim efektima strukturnih lomova. Osnovni cilj doktorske disertacije je
teorijsko-metodološka i empirijska analiza primenljivosti alternativnih modela
za procenu rizika i prinosa na tržištu kapitala Srbije.
Empirijsko istraživanje je, na uzorku stopa prinosa najlikvidnijih akcija
kotiranih na Beogradskoj berzi, ukazalo da tradicionalni CAPM model nije
prikladan za korišćenje na srpskom tržištu kapitala. Mere rizika negativnih
odstupanja stopa prinosa i modeli za procenu rizika i prinosa zasnovani na njima
imaju značajno veću sposobnost opisivanja varijacija u prosečnim stopama prinosa
od klasičnih beta i CAPM modela. Budući da je na srpskom tržištu kapitala učešće
nesistematskog u ukupnom riziku relativno visoko, mera rizika zasnovana na
poludevijaciji, odnosno odgovarajući model za procenu rizika i prinosa, najbolje
opisuje varijabilnost prosečnih stopa prinosa od svih ispitivanih modela.
Testiranje uslovnog CAPM modela je pokazalo da postoji izvestan stepen
promenljivosti beta i tržišnih premija rizika, ali da variranje varijabli u
vremenu nije dovoljno veliko da bi uslovni model rezultirao mnogo boljim
performansama od bezuslovnog. Rezultati su pokazali da modeli za procenu rizika i
prinosa koji uključuju strukturne lomove mogu bolje da objasne varijacije u stopama
prinosa.ABSTRACT:
For many years many authors have tried to formulate an adequate asset pricing model. One
of the first such models is Capital asset pricing model (CAPM) in which the security’s
expected rate of return is proportional to its systematic risk measured by beta
coefficient. Given that the CAPM model was the subject of many theoretical discussions, as
well as empirical challenges, many authors have advocated the use of alternative models.
The subject of the doctoral thesis are alternative asset pricing models on the capital market
of Serbia. Special attention is paid to testing of the applicability of unconditional CAPM
model, downside CAPM models, a model with a risk measure based on semideviation,
conditional CAPM model in which the beta and market risk premium vary in time and the
models that includе the effects of structural breaks. The main objective of the doctoral thesis
is theoretical and methodological, as well as empirical analysis of the applicability of
alternative asset pricing models in the capital market of Serbia.
Empirical research on the sample of rates of return of the most liquid stocks listed on the
Belgrade Stock Exchange revealed that the traditional CAPM model is not suitable for use
in the Serbian capital market. Downside risk measures and asset pricing models based on
them have a significantly greater ability to describe the variations in the average rates of
return than the classic beta and the CAPM model. Since the share of the non-systematic risk
in total risk is relatively high in the Serbian capital market, a measure of risk based on
semideviation and an appropriate asset pricing model best describe the variability of the
average rates of returns of all tested models. Testing of the conditional CAPM model has
shown that there is a certain degree of variability in betas and market risk premiums, but
time fluctuations in variables are not large enough to make conditional model better
performing than unconditional. The results show that the asset pricing models that include
structural break had somewhat greater ability to describe the variations in the rates of return
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