Is there a scale of record group/collection accuracy?
When viewed as a whole (as a statistical mass) there may be some scientific basis for assessing the validity of historical record group or collection information. This might in part draw on the approaches in methodology/science that are used to develop and assess the reliability of research surveys and the like.
Such assessment would not be nearly so cut and dry or meaningful in terms of the work of genealogists and family historians, especially because
- We are not dealing with the norm, but with the individual records and the bits of information found in the record groups and collections. Statistically speaking, these individual entries/bits of information vary widely as to their degree of "accuracy"; any one entry/bit has greater probability of error and omission.
- Only sometimes do genealogists set out to use information in a manner consistent the original intent of that information." In other words, it is only is my folly to believe the US government took the 1850 census so that I would know how old my John Miller then really was.
While I am light on the science to back it up, I believe there is some general qualitative assessment at work in genealogy—probably among record/source types rather than between them. For example, take an 1850 era baptismal record entered by a traveling preacher from Pennsylvania and the same era Norwegian parish record. Whether is it bias or not, I would initially place more weight or give more credence to the Norwegian record. Between a traveling preacher a and a traveling preacher b, though, all my bets are off lack material study about the two record sets.
Generally speaking, and in my own words, our science is different because our interest is unique. The Genealogical Proof Standard talks about a reasonably exhaustive search including review/exposure to a wide variety to high quality sources.* What this has meant to me is seeking diversity in the records I'm using, the quest for something closer to a 360 degree perspective on the information/evidence.
*Genealogists categorize sources as to whether each is an original or derivative. A common comparison could be a marriage record (original) vs an abstracted or indexed entry about that same marriage record (derivatives). Even working with an original, there may be more value to viewing that original in the context of the original record book. Take the example of a parish register entry or a New England birth/marriage/death recorded in the town books or records--viewing the entries in sequence often provides better contextual information than viewing the a single, isolated record.