Office Spreadsheet Analysis

Use this skill when the job is not just "open Excel" but to understand a workbook, keep it trustworthy, and extract the signal.

Use when

• A workbook, CSV, or spreadsheet export is the primary input.
• The user needs anomaly detection, period comparison, trend analysis, or a cleaned business summary.
• You need to edit an existing workbook without breaking formulas or conventions.

Do not use when

• The real source of truth is a DOCX, PDF, or email thread and the spreadsheet is secondary.
• The user only wants a generic text summary with no spreadsheet handling.

Spreadsheet rules that matter

• Preserve existing template and styling conventions when updating a workbook.
• Keep calculations dynamic. If a number should remain updateable, prefer formulas over hardcoded output.
• If formulas are introduced or changed, verify that no formula errors were created.
• Distinguish between raw data tabs, calculation tabs, and presentation tabs before changing anything.
• When one workbook is acting like a dataset rather than a presentation artifact, prefer DuckDB-style file querying for heavier exploration.

Workflow

Step 1: Read the workbook shape

Understand:

• which sheets are raw inputs
• which sheets are calculations
• which sheets are presentation outputs
• where assumptions live
• what date or period logic the workbook is using

Do not start editing cells blindly.

Step 2: Decide the working mode

Choose one:

• analysis only
• data cleanup
• workbook update
• model extension

The working mode changes how aggressive you should be with edits.

Step 3: Check trust before insight

Before reporting conclusions, validate:

• headers and units
• missing values
• duplicate rows
• formula integrity
• stale period or scenario assumptions

If the workbook is not trustworthy yet, say that before summarizing.

Step 4: Run the analysis

Typical outputs:

• variance vs prior period
• rank / top contributors
• anomaly list
• trend summary
• segment comparison
• scenario or sensitivity readout

Keep business interpretation tied to what the sheet actually supports.

Step 5: If editing, preserve future usefulness

When changing the workbook:

• put assumptions in separate cells where possible
• avoid baking calculations into values
• keep worksheet logic readable
• verify formulas after saving

Output format

Return:

1. Workbook read

• key sheets
• likely source-of-truth tabs
• notable structural risks

2. Data quality check

• what looks reliable
• what needs caution

3. Findings

• main trends
• anomalies
• comparisons

4. If edits were made

• what changed
• why
• what still needs verification

Use together with

• xlsx for file handling and workbook-safe operations
• office-duckdb-read-file and office-duckdb-query when spreadsheet work turns into multi-file or SQL-style analysis
• office-source-reconciliation when the numbers must be checked against documents or PDFs