42,090 research outputs found
Mining and Analyzing the Italian Parliament: Party Structure and Evolution
The roll calls of the Italian Parliament in the XVI legislature are studied
by employing multidimensional scaling, hierarchical clustering, and network
analysis. In order to detect changes in voting behavior, the roll calls have
been divided in seven periods of six months each. All the methods employed
pointed out an increasing fragmentation of the political parties endorsing the
previous government that culminated in its downfall. By using the concept of
modularity at different resolution levels, we identify the community structure
of Parliament and its evolution in each of the considered time periods. The
analysis performed revealed as a valuable tool in detecting trends and drifts
of Parliamentarians. It showed its effectiveness at identifying political
parties and at providing insights on the temporal evolution of groups and their
cohesiveness, without having at disposal any knowledge about political
membership of Representatives.Comment: 27 pages, 14 figure
VizRank: Data Visualization Guided by Machine Learning
Data visualization plays a crucial role in identifying interesting patterns in exploratory data analysis. Its use is, however, made difficult by the large number of possible data projections showing different attribute subsets that must be evaluated by the data analyst. In this paper, we introduce a method called VizRank, which is applied on classified data to automatically select the most useful data projections. VizRank can be used with any visualization method that maps attribute values to points in a two-dimensional visualization space. It assesses possible data projections and ranks them by their ability to visually discriminate between classes. The quality of class separation is estimated by computing the predictive accuracy of k-nearest neighbor classifier on the data set consisting of x and y positions of the projected data points and their class information. The paper introduces the method and presents experimental results which show that VizRank's ranking of projections highly agrees with subjective rankings by data analysts. The practical use of VizRank is also demonstrated by an application in the field of functional genomics
Quantifying discrepancies in opinion spectra from online and offline networks
Online social media such as Twitter are widely used for mining public
opinions and sentiments on various issues and topics. The sheer volume of the
data generated and the eager adoption by the online-savvy public are helping to
raise the profile of online media as a convenient source of news and public
opinions on social and political issues as well. Due to the uncontrollable
biases in the population who heavily use the media, however, it is often
difficult to measure how accurately the online sphere reflects the offline
world at large, undermining the usefulness of online media. One way of
identifying and overcoming the online-offline discrepancies is to apply a
common analytical and modeling framework to comparable data sets from online
and offline sources and cross-analyzing the patterns found therein. In this
paper we study the political spectra constructed from Twitter and from
legislators' voting records as an example to demonstrate the potential limits
of online media as the source for accurate public opinion mining.Comment: 10 pages, 4 figure
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