Leading With Data· a Bicycle Guide

Partial book profile

Guerrilla Data Analysis Using Microsoft Excel Conquering Crap Data and Excel Skirmishes Excel Skirmishes

A practical, mission-driven guide that teaches accidental and self-taught data workers how to conquer messy 'crap data' and win real-world 'skirmishes' using modern Excel tools like Power Query, Pivot Tables, XLOOKUP, and dynamic arrays.

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What it’s about

If spreadsheets keep landing in your inbox and you've become an 'unwitting data analyst' without formal training, this book is your survival kit. Oz du Soleil and Bill Jelen frame data work as guerrilla combat against duplicate entries, incomplete records, sloppy cut-and-paste jobs, and data scattered across dozens of places. Beyond teaching the newest Excel features (Power Query, dynamic arrays, LET, XLOOKUP, data types), the book emphasizes the 'skirmishes'—the human and process problems outside Excel that make analysis miserable: octopus spreadsheets, working on source data, deciding when data is 'clean enough,' and identifying whether you have a people, process, or tool problem. Full of practical examples across nonprofits, accounting, retail, and event planning, it teaches you to be functional (not an expert), to be responsible for your own solutions, and above all to remember the people who depend on your work being accurate and on time.

The through-line

Who it’s for
A self-taught or accidental data worker—someone in a data-driven role without formal data training—who wants to confidently and accurately turn messy data into useful results.
The problem
They are handed messy, inconsistent, duplicate-ridden, scattered 'crap data' and expected to produce accurate analysis and reports. They feel blindsided, overwhelmed, anxious under pressure, and afraid their lack of formal training or 'mastery' will be exposed.
The plan
  1. Review the fundamentals (references, IF, text functions, sorting, filtering) to get functional.
  2. Make data dynamic with Excel Tables, Pivot Tables, and clean linked worksheets.
  3. Use Power Query to import, clean, split, merge, unpivot, and consolidate crap data.
  4. Apply lookups (XLOOKUP), dynamic arrays, LET, and conditional formatting to analyze and flag issues.
  5. Protect integrity with data validation, sheet protection, crossfooting, and row counts.
The payoff
You turn a weekend of manual work into 30 seconds with a Pivot Table. · Your spreadsheets update automatically and maintain their integrity as data changes. · You confidently clean, merge, and consolidate data from many sources.

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Additional reading

  • Excel Tables: A Complete Guide for Creating, Using, and Automating Lists and Tables · Zack Barresse and Kevin Jones

    Recommended by the author for a deep dive into Excel Tables, which he presents as a foundational and underused feature for creating dynamic spreadsheets.

  • Master Your Data with Power Query in Excel and Power BI · Ken Puls and Miguel Escobar

    Cited as a key resource for readers wanting to go beyond the book's introduction to Power Query, a tool the author champions for data cleansing and transformation.

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