Consistency checks
Checked against the source, not assumed.
We ask what the audience looks like before asking how many there are. Checks run against the output, not against the intention. The file ships with its own limitations written down.
Segment design
Deciding the cuts with you, against what the data can actually support.
Supply assessment
Saying plainly where the available data stops, including when it stops short of the brief.
Universe sizing
Establishing how many records satisfy the criteria before anyone decides whether the job is worth running.