Automate data analysis: from spreadsheets to recurring reports

4 min readUpdated Skillshop operator and creator of the Maker Evan YouTube channel

Translated from Korean. View original. Some screenshots are available in Korean only.

If you repeatedly combine Excel files and normalize dates, start by automating data preparation. Keep the originals and ask to compare row counts, totals and date ranges. Consider what to delegate and what checks to retain from collection through recurring reports.

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View original Korean screenshot
스킬샵의 데이터·엑셀 카테고리 화면. 데이터 정리와 자동화를 다루는 스킬 카드가 놓여 있다.
스킬샵에서 관련 작업의 스킬과 사용 예시를 살펴볼 수 있어요.

Find repeated preparation work

List repeated operations such as merging files, normalizing columns and dates, and checking duplicates. For a report from last week, separate preparation, calculation and interpretation.

Delegate preparation to an AI tool that can read and save files, but keep the originals separately. Define what to analyze and how the result will be used before starting.

PrepareMerge files, normalize columns and dates, and check duplicates.
CalculateApply aggregation and calculations to the prepared table.
DecideChoose metrics, assess whether numbers make sense and determine action.
Start by listing operations that repeat the same rules.

Start with work whose results can be checked

Column cleanup, conditional row extraction and aggregation lend themselves to checks against the source. If removing duplicates, specify which columns define a duplicate.

You can ask AI for metric or interpretation suggestions, but distinguish facts verified in the data from guesses and review final metrics and conclusions against the work’s purpose.

Check against the source
  • Merge and normalize files
  • Handle duplicates and blanks
  • Create pivots, aggregates and charts
  • Repeat fixed calculations
Review against the purpose
  • Choose metrics
  • Interpret causes
  • Decide how to handle unusual values
  • Set conclusions and next actions
Column cleanup, extraction and aggregation can be compared with the source.

Missing rows may produce no error

A merged file may open normally even when rows are missing. Record and compare row counts, key totals and earliest and latest dates before and after transformation.

Spot-checking rows helps, but a few correct rows do not prove the whole result. Also check error-prone cases such as duplicates, blanks, negatives and date boundaries.

RowsDo counts match before and after merging?
TotalsDo key numeric totals match the source?
PeriodAre the earliest and latest dates unchanged?
SamplesCompare samples and error-prone rows against the source.
A file can open normally even when merged rows are missing.

Prepare tables for calculation

Multiple header rows or merged cells can cause the start of the data to be read incorrectly. In a calculation copy, use one header row, one value per cell and no merged cells.

Preserve original formulas and check that values used for aggregation are current. Separate the original, cleaned data and aggregate results so you can trace the calculation.

Table formatted for people
  • Several sheets
  • Two header rows
  • Merged cells
Table used for calculation
  • One header row
  • One value per cell
  • No merged cells
Multiple headers and merged cells can obscure where data begins.

Save sources when collecting web data

Changes to page structure or login can stop a crawler or produce wrong values. Check that required fields were collected; consider an authorized API or export if available.

Collect in batches and keep intermediate results and collection times so you can restart at a failure. Check the terms for using the data.

Collect in batchesSave intermediate results instead of collecting everything at once.
Preserve originalsKeep received files unchanged.
Clean a copyRecover from preparation errors without collecting again.
Changes to a page or login can stop collection or yield wrong values.

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View original Korean screenshot
스킬샵의 자동화 AI 스킬 카테고리 화면. 업무와 채널 자동화를 다루는 스킬 카드가 격자로 놓여 있다.
관련 스킬과 제작자, 사용 예시를 살펴볼 수 있는 스킬샵 화면이에요.

Set report format and exception rules

For a weekly report, define the period, metrics, order and save location. Place changes from the prior period consistently so readers can find them.

Mark missing values as missing rather than guessing. Flag outliers rather than discarding them arbitrarily, then handle them under your business rules.

Fixed formatPut the same items in the same positions.
ChangeShow what differs from the prior report.
Missing valuesMark blanks instead of filling them.
OutliersDecide in advance whether to remove or flag them.
Set period, metrics, order and location for recurring reports.

Browse related skills, creators and examples on Skillshop.

View original Korean screenshot
스킬샵 문서/PPT 카테고리 화면. 스킬 2개가 카드로 놓여 있고 카드마다 썸네일과 별점, 사용자 수, 가격이 붙어 있다.
관련 스킬과 제작자, 사용 예시를 살펴볼 수 있는 스킬샵 화면이에요.

Choose tools for where the data lives

Start with a file-capable AI tool for local files. For an internal database or external service, consider an API, export or MCP connection.

Public spreadsheet and document skills contain file-processing and review procedures. Check support for your file format and environment, then try one small file from input through saving.

ToolFunctionWhen useful
AgentReads and processes files using supported features.Calculations and file preparation.
MCPA connection to external tools and data.Querying internal databases or external services.
SkillConveys steps and validation as instructions.Repeating a procedure.
Choose for the data location and task; APIs or exports are alternatives for external data.
SkillInstructions for preparation and checks.
AgentOpens, edits and saves files using supported features.
MCPOne way to connect to external data.
Start local files with a tool that can process files.
Pre-built Agent Skills in Anthropic's English documentation
An example from the official documentation; check the current linked guidance.Source: Claude Platform documentation
Open full-size image (opens in a new tab)
View original Korean screenshot
앤트로픽 공식 문서의 사용 가능한 Skills 목록. 사전 구축된 스킬로 PowerPoint(pptx)·Excel(xlsx)·Word(docx)·PDF 네 개가 적혀 있고, 아래에 오픈소스 Skills 항목이 이어져요.
공식 문서의 화면 예시예요. 현재 설정은 연결된 공식 안내에서 확인해 주세요.출처: 앤트로픽 공식 문서 · Agent Skills

Save a successful procedure as a skill

Record input files, preparation rules, totals to check and output format in SKILL.md. Ask it to stop and report differences if totals do not match.

Share sample inputs and expected results with the team. A second person running the same procedure can find missing explanations.

Browse related skills, creators and examples on Skillshop.

View original Korean screenshot
스킬샵 문서/PPT 카테고리 화면. 문서와 리포트를 다루는 스킬 카드가 놓여 있다.
관련 스킬과 제작자, 사용 예시를 살펴볼 수 있는 스킬샵 화면이에요.

Frequently asked questions

How much data analysis can AI handle?

Start with checkable work such as merging files, cleaning columns and aggregating. AI can suggest metrics or interpretations, but distinguish verified facts from guesses and review conclusions against the purpose.

How do I validate prepared data?

Compare row counts, key totals and first and last dates before and after conversion. Spot checks help but do not prove completeness; also check blanks, duplicates, negatives and date boundaries.

What should I do before automating an Excel file?

Make a calculation copy with one header row, one value per cell and no merges. Preserve original formulas, check that calculated values are current and separate source, cleaned and aggregate outputs.

Sources