Internet Archaeol. 25. Richards et al. VASLE. Portable Antiquities Scheme records

4.2.1 Portable Antiquities Scheme records

Restrictions on time made it impossible to consider an assessment of the more recent PAS records as comprehensive as that undertaken for the VASLE 'National dataset'. However, comparison of the PAS records of 'EARLY MEDIEVAL' artefacts (downloaded 30 May 2007) with the final VASLE 'National dataset' suggested that data 'cleaning' sufficient for site comparison could be achieved by applying four principles:

Excluding any object whose primary material is not metal
Excluding any object whose 'date from' is 0 or after 1000
Excluding any object whose 'date to' is 0 or before 700
Excluding any object whose date range was more than 500 years

The first three criteria ensured that the data were relevant to VASLE's focus on coins and metalwork, and its study period in the Middle to Late Saxon era. The final criterion was intended to 'clean' the data by excluding artefacts whose identification was essentially insecure and so might have distorted patterns in the better-quality data.

Examination of the dataset produced by this filtering revealed a number of artefact types still present that were clearly early rather than Middle Saxon. It was therefore decided to apply an additional filter:

If an object could be dated to a range of <250 years, its start date must be after 700

This deleted a relatively small number of records that could be genuinely considered Middle Saxon, but reduced the number of apparently Early Saxon artefacts considerably. Of the remaining artefacts, the overwhelming majority with start-dates before 450 could clearly be identified as Early Saxon, so a final filter was applied:

The start-date of all artefacts must be after 450

This effectively removed the last significant group of Early Saxon artefacts from the dataset.

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