Address standardisation
Where each record came from, and when.
Nothing is assembled before the target is described in writing. Fields that are frequently empty are reported as such rather than quietly filled. Figures are reported as ranges where a single number would overstate what is known.
Address normalisation
Standardising location data before comparison, so one place does not read as several.
Outlier review
Looking at the extremes of each field, because that is where bad data announces itself.
Field standardisation
One definition per column, applied consistently, with original values retained beside the normalised ones.