What counts as evidence

Observation, record, statement, in that order of weight.

Evidence in an audit ranges from watching something happen, through documents produced at the time, to what somebody says now. The weight differs substantially and audits frequently rest on the weakest of the three.

Observation is strongest and is used least, because it takes time and requires being present when the work happens. An auditor who watches a process run learns things no record shows, including all the steps that are not in the procedure.

Contemporaneous records are next. A record created at the time, in a system with a timestamp, is stronger than one produced on request, and the difference matters where a question arises later.

Statements are the weakest and are what most audits are built from, because they are quick. They are useful for direction rather than for conclusion, and a finding resting solely on what somebody said is fragile.

Corroboration across types is what makes a finding solid. Something described in interview, visible in a record, and consistent with what was observed is established; any one alone is an indication.

The other evidence weight worth noting is negative evidence: the absence of a record where one should exist. That is frequently stronger than anything positive, because it cannot be explained by a filing error if the process is supposed to generate a record every time.