Read the gaps as carefully as the data

Historical state#

An account may have a publication date without establishing the date of the configuration it describes. Avoid turning an undated observation into a precise chronology.

Identity and relationships#

Shared names and similar specifications can suggest a relationship without proving identity. Unresolved actor or represented-instrument links should remain unresolved in downstream analysis unless additional evidence supports a decision.

Geographic precision#

Coordinates can refer to locations at different levels of precision. Preserve coordinate qualifications and administrative evidence when making maps or spatial comparisons.

Counts and occurrences#

A source-account row is not necessarily a unique physical component. For example, multiple accounts may describe the same stop at different times. Count the unit that your question actually concerns.

Missing values have different causes#

Keep these distinctions through transformations. Converting all missing values to zero, attaching an arbitrary year or resolving every name by its nearest spelling can make a table easier to compute while changing its meaning. If a method requires complete cases, document the selection rule and assess which sources or regions it disproportionately removes.

Repeated accounts are not independent witnesses#

Agreement across records can be valuable, but sources may copy one another or derive from a shared earlier account. Count supporting records separately from independent evidence. When the transmission relationship is unknown, that uncertainty belongs in the interpretation rather than being replaced by a simple majority vote.

A bounded comparison is often more useful#

For a comparison of specifications, choose a documented unit, date scope and inclusion rule before interpreting differences. Report both what the selected corpus supports and what it cannot answer. A bounded result about attributed accounts can be strong research without claiming to describe every surviving instrument or its present condition.