Suchergebnisse

AbstractThe (unheralded) first step in many applications of automated text analysis involves selecting keywords to choose documents from a large text corpus for further study. Although all substantive results depend on this choice, researchers usually pick keywords in ad hoc ways that are far from optimal and usually biased. Most seem to think that keyword selection is easy, since they do Google searches every day, but we demonstrate that humans perform exceedingly poorly at this basic task. We offer a better approach, one that also can help with following conversations where participants rapidly innovate language to evade authorities, seek political advantage, or express creativity; generic web searching; eDiscovery; look‐alike modeling; industry and intelligence analysis; and sentiment and topic analysis. We develop a computer‐assisted (as opposed to fully automated or human‐only) statistical approach that suggests keywords from available text without needing structured data as inputs. This framing poses the statistical problem in a new way, which leads to a widely applicable algorithm. Our specific approach is based on training classifiers, extracting information from (rather than correcting) their mistakes, and summarizing results with easy‐to‐understand Boolean search strings. We illustrate how the technique works with analyses of English texts about the Boston Marathon bombings, Chinese social media posts designed to evade censorship, and others.

Monetary policy on real estate investment in China has had varying impacts across the country due to regional differences. A supply-determined model is used to measure the policy effects on property investment volume based on a set of regional data from 2003 to 2010. This research yields several important findings contributing to an understanding of uneven policy effects on the unbalanced regional markets. Firstly, it is revealed that the eastern coastal provinces in China have a higher dependence on bank loans for housing investment than that of the other inland provinces. Secondly, this research has disentangled the specific transmission channels of monetary policy in the property market. Bank loan supply, instead of interest rates, would be a potentially effective policy tool for the government in making property market adjustment. Thirdly, the eastern coastal provinces are more sensitive in their responses to the changes of monetary stances than the other non-coastal central and western provinces. Therefore, the government must take note of the significant heterogeneity arising from the regional differences in estimating the policy impacts, although monetary policy is uniformly employed in the nation most of the time.

On the military training facility of Tekong Island, Singapore, a comprehensive vector-borne disease control program was started in end-2006 to reduce mosquito populations and negate the need for anti-malaria chemoprophylaxis. The program was based on 1) preventing importation of malaria through screening of visitors, 2) preventing human-to-mosquito transmission through early case detection and mosquito control, 3) preventing mosquito-to-human transmission through personal protection, and 4) contingency plans. Systematic environmental works were performed to reduce breeding sites, and insecticide use targeted both adult mosquitoes and larvae. Mosquito populations declined from 103 mosquitoes per sampling site in January 2007 to 6 per site by March 2007 (P < 0.001). The proportion of positive ovitraps declined from 93% in January 2007–2% in March 2007 (P < 0.001). There were no malaria cases on the island despite chemoprophylaxis termination, showing that comprehensive combination vector-control strategies were effective in reducing the risk of malaria.