An Examination of the Failure Rate and Content Equivalency of Electronic Surrogates and the Implications for Print Equivalent Preservation

Ken Ladd


Objective – This study sought to determine whether evidence indicates a need to preserve print equivalent journal collections. In addition, this research aimed to provide data on the failure rate of print equivalent materials for possible digitization to replace existing poor quality or defective electronic surrogates.

Methods – The project compared the content of randomly selected journal titles, volumes, and issues from seven electronic journal archives and their print equivalents held at the University of Saskatchewan Library. The archives were obtained from five separate vendors representing humanities, social sciences, science, technology, and medicine. Data were collected on the frequency and types of failure of electronic surrogates, supplemental content missing from electronic surrogates, and frequency and types of failure of print equivalent materials.

Results – Across all electronic journal archives the failure rate of electronic surrogates was 7.5% for all PDF documents and 11.5% for scholarly PDF documents. For individual electronic journal archives the failure rate ranged from 0.7% to 19.5% for all PDF documents and from 0.3% to 26.5% for scholarly PDF documents. Data is presented on the failure rate of individual electronic journal archives, types of failure, and missing supplemental content. An examination of print equivalent titles found 1.7% of print scholarly articles could not be used or were not optimal for digitization.

Conclusions – The study demonstrates the need for preserving print equivalent journal titles for at least the short (less than 5 years) to medium term (up to 10 years), while poorly digitized materials are identified, replaced, and digitally preserved. While electronic surrogates of image-rich scholarly papers are more likely to have quality issues, the study found some text-only PDF scholarly documents were illegible, indicating the need for caution against liberally applying this as a criterion for disposal of print equivalent titles. There is significant supplemental content absent from electronic surrogates which indicates a need for further discussion of the necessity for such information or for incorporating it into the digitization process to ensure a complete record of the print equivalent journals for future use. The failure rate of print equivalent titles for possible digitization provides additional data for discussions related to the determination of optimal overlap. It also suggests that the number of copies required for a full set of preserved journals over a specified time horizon may be greater than anticipated, unless page level validation is performed.


print preservation; electronic surrogate; print equivalent; content equivalency; failure rate

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