Estimation Methods for the Size of Deep Web Textural Data Source: A Survey
Jie Liang · 2008
The estimation of the size of deep web data sources has been an open problem since 1998. This survey reviews all papers that were available online, and other, resources, on estimating the size of data sources during the period 1998 to 2008. In the survey, we rst clarify several basic terms that are used in the survey but whose meanings vary in the literature. Basic models in the literature on estimation are also discussed. The survey introduces query-based sampling approaches and reviews the estimation methods of estimating relative size and actual size of data source(s). Querybased sampling is biased. The survey also reviews research on overcoming biases caused by various estimation methods. Finally, the future direction of estimation is discussed.