Using Capture-Recapture approach estimate size of Web databases

In order to estimate the size of Web database,this paper proposed the Capture-Recapture based estimation methods that filtered out two words intimate and rejection cases.Submitting attributed high-frequency words in the text box of query interface,using the returned result,in the intersection of two results analyzing the independence of two sampling,filtering the dependent couples,and then using Capture-Recapture method estimated the size of Web database.In the simulated and real environment for the experiment,the bias and the volatility of the method are smaller.