Prerequisites
Source criticism, sampling versus selection, proportions, and bounds.
Distinguish a surviving archive from the population of records originally produced. If survival depends on content, observed proportions need not represent the original collection. Bounds can express what is identified without inventing a missing-data mechanism.
Worked example
If 30 of 50 surviving petitions support a policy, 60% describes survivors. Without knowing which records were lost, it does not establish support among all original petitions, still less among all residents.
Model and Assumptions
Fictional archive: an inventory establishes 100 original petitions. Forty survive, of which 30 explicitly support a proposal and 10 oppose it. Sixty are unavailable. Assume each original petition was either supportive or opposed, with no duplicates; survival may be selective.
Further inquiry
Derive bounds when the number of original petitions is known only to lie between 90 and 110. Then specify which evidence could narrow survival uncertainty without assuming that silence means opposition.
Review criteria
- Keep the 40 observed petitions fixed while varying the total.
- Derive a lower bound of 30/110 and an upper bound of 100/110.
- Separate record survival, record production, and population opinion.