Dank or Not? -- Analyzing and Predicting the Popularity of Memes on Reddit

Internet memes have become an increasingly pervasive form of contemporary social communication that attracted a lot of research interest recently. In this paper, we analyze the data of 129,326 memes collected from Reddit in the middle of March, 2020, when the most serious coronavirus restrictions were being introduced around the world. This article not only provides a looking glass into the thoughts of Internet users during the COVID-19 pandemic but we also perform a content-based predictive analysis of what makes a meme go viral. Using machine learning methods, we also study what incremental predictive power image related attributes have over textual attributes on meme popularity. We find that the success of a meme can be predicted based on its content alone moderately well, our best performing machine learning model predicts viral memes with AUC=0.68. We also find that both image related and textual attributes have significant incremental predictive power over each other.

Copula-based anomaly scoring and localization for large-scale, high-dimensional continuous data

The anomaly detection method presented by this paper has a special feature: it does not only indicate whether an observation is anomalous or not but also tells what exactly makes an anomalous observation unusual. Hence, it provides support to localize the reason of the anomaly. The proposed approach is model-based; it relies on the multivariate probability distribution associated with the observations. Since the rare events are present in the tails of the probability distributions, we use copula functions, that are able to model the fat-tailed distributions well. The presented procedure scales well; it can cope with a large number of high-dimensional samples. Furthermore, our procedure can cope with missing values, too, which occur frequently in high-dimensional data sets. In the second part of the paper, we demonstrate the usability of the method through a case study, where we analyze a large data set consisting of the performance counters of a real mobile telecommunication network. Since such networks are complex systems, the signs of sub-optimal operation can remain hidden for a potentially long time. With the proposed procedure, many such hidden issues can be isolated and indicated to the network operator.

Data-driven Analysis of Complex Networks and their Model-generated Counterparts

Data-driven analysis of complex networks has been in the focus of research for decades. An important question is to discover the relation between various network characteristics in real-world networks and how these relationships vary across network domains. A related research question is to study how well the network models can capture the observed relations between the graph metrics. In this paper, we apply statistical and machine learning techniques to answer the aforementioned questions. We study 400 real-world networks along with 2400 networks generated by five frequently used network models with previously fitted parameters to make the generated graphs as similar to the real network as possible. We find that the correlation profiles of the structural measures significantly differ across network domains and the domain can be efficiently determined using a small selection of graph metrics. The goodness-of-fit of the network models and the best performing models themselves highly depend on the domains. Using machine learning techniques, it turned out to be relatively easy to decide if a network is real or model-generated. We also investigate what structural properties make it possible to achieve a good accuracy, i.e. what features the network models cannot capture.