Checking work produced by an AI spreadsheet assistant

Freeze the question and the workbook version

Suppose a synthetic operations team asks an assistant to explain a quarterly budget variance. The workbook has Actuals, Budget, and Mapping tabs. An assistant returns a neat chart showing a 12% overspend in one cost centre. Before accepting that figure, the analyst needs to know which quarter, currency, version, cost-centre mapping, and expense categories the chart includes. The starting workbook is saved as a separate version, and the question is restated in those terms. This is not bureaucracy: it gives the reviewer a fixed baseline against which to compare AI edits.

The Microsoft support page on Copilot in Excel data insights describes features such as generating formulas, summaries, charts, and PivotTables, and explicitly tells users to review and verify generated content. That is an example of a current vendor's documented capability, not a claim that all spreadsheet assistants work identically. The Microsoft Copilot in Excel FAQ says AI-generated results can be inaccurate and notes that saved workbook changes may be visible to others with access. A team should check its own product version and access settings before deciding how to handle a workbook.

Sources: [1] [2]

Use a lineage table to test the result

The synthetic analyst creates a four-column lineage table: output claim, source range, transformation, and independent check. For “12% overspend,” the source range should name the actual and budget rows and the Mapping tab version used to assign the cost centre. The transformation should show the formula and whether it treats the difference as a percentage of budget or actuals. The independent check recalculates the value from a small sample or a separate formula. If the denominator is unclear, the chart's headline remains unresolved.

The reviewer also inspects hidden rows, filters, totals, blank cells, and formula references. A chart can be arithmetically correct for the visible table but wrong for the decision because a late adjustment row was excluded. If a formula was inserted, compare it with adjacent rows and test an edge case: zero budget, a negative credit, or an unmapped category. If an assistant produced text rather than changing cells, still trace each stated number to its workbook source. The deliverable is not the assistant's answer; it is the reviewed workbook plus the lineage table.

Microsoft's guidance on workbook change history explains that Copilot reports only changes available in the workbook's change history. This is why a reviewer should preserve a version and use the underlying change and version controls rather than assume a conversational recap is a complete audit trail. Other products may offer different controls, so the test is to verify the actual environment, not to infer an absence of logging or visibility.

Sources: [3]

Separate calculation from interpretation

Even after the 12% figure is reproduced, “overspend” may be an interpretation that needs context. Perhaps the budget tab is pre-reallocation while the actuals include an approved transfer. The analyst should confirm the accounting definition and report the caveat beside the figure. A reviewer who only checks the formula may miss that the wrong business comparison was chosen. The final slide can state the reviewed calculation, the source version, and the unresolved mapping question rather than present the assistant's first phrasing as fact.

For a high-consequence workbook, the team may require a second person to inspect the lineage table and approve the export. For a low-consequence exploratory chart, a lighter check may suffice. The choice depends on the decision being made. This example is synthetic; it does not establish a product benchmark or claim that any assistant always makes a particular error. Two Prune's assessment product can observe task-bounded spreadsheet reasoning and available verification evidence for human interpretation, but it is not a general spreadsheet audit service or an automated employment decision tool.