Estimating Absolute Web Crawl Coverage From Longitudinal Set Intersections

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Hauptverfasser: Paris, Michael, Paris, Grigori, Baumann, Fabian
Format: Preprint
Veröffentlicht: 2026
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author Paris, Michael
Paris, Grigori
Baumann, Fabian
author_facet Paris, Michael
Paris, Grigori
Baumann, Fabian
contents Web archives preserve portions of the web, but quantifying their completeness remains challenging. Prior approaches have estimated the coverage of a crawl by either comparing the outcomes of multiple crawlers, or by comparing the results of a single crawl to external ground truth datasets. We propose a method to estimate the absolute coverage of a crawl using only the archive's own longitudinal data, i.e., the data collected by multiple subsequent crawls. Our key insight is that coverage can be estimated from the empirical URL overlaps between subsequent crawls, which are in turn well described by a simple urn process. The parameters of the urn model can then be inferred from longitudinal crawl data using linear regression. Applied to our focused crawl configuration of the German Academic Web, with 15 semi-annual crawls between 2013-2021, we find a coverage of approximately 46 percent of the crawlable URL space for the stable crawl configuration regime. Our method is extremely simple, requires no external ground truth, and generalizes to any longitudinal focused crawl.
format Preprint
id arxiv_https___arxiv_org_abs_2603_15416
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Estimating Absolute Web Crawl Coverage From Longitudinal Set Intersections
Paris, Michael
Paris, Grigori
Baumann, Fabian
Physics and Society
Digital Libraries
Information Retrieval
Information Theory
82
H.3.3
Web archives preserve portions of the web, but quantifying their completeness remains challenging. Prior approaches have estimated the coverage of a crawl by either comparing the outcomes of multiple crawlers, or by comparing the results of a single crawl to external ground truth datasets. We propose a method to estimate the absolute coverage of a crawl using only the archive's own longitudinal data, i.e., the data collected by multiple subsequent crawls. Our key insight is that coverage can be estimated from the empirical URL overlaps between subsequent crawls, which are in turn well described by a simple urn process. The parameters of the urn model can then be inferred from longitudinal crawl data using linear regression. Applied to our focused crawl configuration of the German Academic Web, with 15 semi-annual crawls between 2013-2021, we find a coverage of approximately 46 percent of the crawlable URL space for the stable crawl configuration regime. Our method is extremely simple, requires no external ground truth, and generalizes to any longitudinal focused crawl.
title Estimating Absolute Web Crawl Coverage From Longitudinal Set Intersections
topic Physics and Society
Digital Libraries
Information Retrieval
Information Theory
82
H.3.3
url https://arxiv.org/abs/2603.15416