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Guide Notes & Explanation
Accompanying breakdown for this slide deck
- Your Raw Data's Makeover Starts Here
The Transformation Goal
- Turn messy, raw data into a clean format
- Ensure data is accurate and consistent
- Structure data for easy analysis
- Build a reliable foundation for your reports
- Make your data models more efficient
- Save time during the report creation phase
- Enable powerful and trustworthy insights
Meet Power Query
- This is the built-in engine for data transformation
- Access it through the Power Query Editor window
- Connect to hundreds of different data sources
- Perform all cleaning steps in one place
- See a preview of your changes instantly
- Every action is recorded as an applied step
- Your original data source remains untouched
Essential Cleaning Steps
- Remove unnecessary columns and rows
- Fix data type errors (text to numbers, dates)
- Replace null or error values appropriately
- Rename columns to be clear and consistent
- Trim text to remove extra spaces
- Filter out irrelevant or duplicate records
- Standardize text cases for uniformity
Pivoting and Unpivoting Data
- Unpivot columns to transform them into rows
- This is crucial for data stored in a wide format
- It creates a tall, skinny, analysis-friendly table
- Pivot rows to transform them into columns
- Use this to create summary matrices
- These are some of the most powerful transformations
- Master them to handle any spreadsheet layout
Creating Custom Columns
- Use the Add Column tab to create new data
- Write custom formulas with the M language
- Perform calculations based on other columns
- Merge data from multiple columns into one
- Split text columns using delimiters
- Create conditional logic with if-then-else statements
- Extend your data model with bespoke metrics
Best Practices to Follow
- Always review applied steps for efficiency
- Use descriptive names for your queries and columns
- Group similar queries together for organization
- Leverage parameters for dynamic data sources
- Document your process within the Advanced Editor
- Refresh your data to test the transformation
- Build once and automate for all future reports