Oil rents and the tenure of the leaders in Africa

It is often underlined that African oil producing countries are politically unstable as a result of this natural resource. Based on the data relating to the duration in office of 101 heads of States exercises of power of 26 African countries (North Africa and Sub-Saharan Africa), our study finds that: this instability does not appear in the executive branch of the state. Conversly, using survival analysis including non-parametric and parametric estimators, and controlling for many factors which affect the leader's tenure, our results suggest a positive link between oil rents and the duration in office of the leader. While other minerals rents do not appear to have the same effect. An interpretation of these results is that oil has a strategic aspect that other mining products do not have. Hence, no matter what the type of political regime is in country, the international community is tempted to exert fewer pressures for the change of the leader in an oil producing State.Duration models

Basic tasks of sentiment analysis

Subjectivity detection is the task of identifying objective and subjective sentences. Objective sentences are those which do not exhibit any sentiment. So, it is desired for a sentiment analysis engine to find and separate the objective sentences for further analysis, e.g., polarity detection. In subjective sentences, opinions can often be expressed on one or multiple topics. Aspect extraction is a subtask of sentiment analysis that consists in identifying opinion targets in opinionated text, i.e., in detecting the specific aspects of a product or service the opinion holder is either praising or complaining about

Comprehensive Review of Opinion Summarization

The abundance of opinions on the web has kindled the study of opinion summarization over the last few years. People have introduced various techniques and paradigms to solving this special task. This survey attempts to systematically investigate the different techniques and approaches used in opinion summarization. We provide a multi-perspective classification of the approaches used and highlight some of the key weaknesses of these approaches. This survey also covers evaluation techniques and data sets used in studying the opinion summarization problem. Finally, we provide insights into some of the challenges that are left to be addressed as this will help set the trend for future research in this area.unpublishednot peer reviewe