Only One Out of Five Archived Web Pages Existed as Presented

Abstract

When a user retrieves a page from a web archive, the page is marked with the acquisition datetime of the root resource, which effectively asserts "this is how the page looked at a that datetime." However, embedded resources, such as images, are often archived at different datetimes than the main page. The presentation appears temporally coherent, but is composed from resources acquired over a wide range of datetimes. We examine the completeness and temporal coherence of composite archived resources (composite mementos) under two selection heuristics. The completeness and temporal coherence achieved using a single archive was compared to the results achieved using multiple archives. We found that at most 38.7% of composite mementos are both temporally coherent and that at most only 17.9% (roughly 1 in 5) are temporally coherent and 100% complete. Using multiple archives increases mean completeness by 3.1-4.1% but also reduces temporal coherence.

Adding the Dimension of Time to HTTP

“…In Figure 14.23, we see a NOAA page with a Memento-Datetime of January 29, 1999 with an embedded image as the primary content. However, when we dereference the URI-M for the image, we see that the Last-Modified and Memento-Datetime headers (Figure 14 In our study of temporal violations (Ainsworth et al, 2015), we found that approximately 76% of composite Mementos were complete (i.e., missing no embedded Mementos), and utilizing additional Memento-enabled web archives could raise that number to 80% complete. More concerning is that 6% of composite Mementos are Prima Facie Violative and 2.5% are Probably Violative.…”

From archive to analysis: accessing web archives at scale through a cloud-based interface

“…Not mentioned at length is that the Wayback Machine itself reflected an early and important move towards accessibility. Launched in 2001, seven years after the Internet Archive's 1996 establishment, the Wayback Machine's ubiquity and simplicity disguises the technical complexity inherent in stitching together images, HTML files, and other resources together in relatively temporally-coherent pages (Ainsworth et al 2015). Before 2001, users had to use the command line and servers to work with web archives; now we can view them, albeit one by one.…”

What's cached is prologue: Reviewing recent web archives research towards supporting scholarly use

“…I focus here on studies that compare coverage between collections for a particular research topic or domain, as opposed to general quantitative evaluation of an archive's coverage compared to what exists on the live web (e.g. Ainsworth et al, 2011;Ainsworth et al, 2015;Brunelle et al, 2015). For example, Brügger (2013a) considers the coverage of material relating to Danish parliamentary elections by comparing historical network graphs available from the Danish Netarkivet collection and the Internet Archive.…”