Fayyad and Uthursamy (2002) have stated that the majority of the work (representing months or years) in creating a data warehouse is in cleaning up duplicates and resolving other anomalies. This article provides an overview of two methods for improving quality. The first is data cleaning for finding duplicates within files or across files. The second is edit/imputation for maintaining business ...

The recent development of the Internet has made an increasing number of information sources available to users. This makes it necessary to submit queries only to the most appropriate sources. When gathering and combining information from these sources the quality ooered can and must be a criterion for source selection. However, information quality has many dimensions and it is thus diicult to d...

the wide availability of data on air pollutant emissions, the knowledge already achieved on theset of chemical and photochemical reactions in the troposphere, the ability to access real time weatherconditions at the local scale that determine the transport and transformation of gases and aerosol, now make it possible to obtain credible and reliable predictions, retrospective analyses and/or fut...