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Guide Notes & Explanation
Accompanying breakdown for this slide deck
- Your Power BI Data is a Mess. Let's Fix It.
Why Clean Data?
- Clean data builds trust in your reports
- Accurate data leads to better business decisions
- It prevents errors and misleading visuals
- Saves time during analysis and troubleshooting
- Forms a solid foundation for all your metrics
- It is the most crucial step in any project
Remove Duplicate Rows
- Find the option in the Home or Transform ribbon
- Power Query identifies duplicates across all columns
- Select specific columns to check for duplicates only there
- Review the preview before removing to avoid mistakes
- Removes all but the first instance of a duplicate entry
- Essential for accurate count and sum calculations
Unpivot Your Data
- Turns columns into rows for proper analysis
- Fixes data spread across many column headers
- Select the columns you want to keep as identifiers
- Choose the columns to unpivot (often date or category columns)
- Creates two new columns: Attribute and Value
- Transforms wide, messy data into a tall, clean format
Split Columns Easily
- Break one column into multiple new columns
- Use by delimiter like a comma, space, or hyphen
- Choose to split at each occurrence or a specific number
- Split by number of characters for fixed-width data
- You can split into rows instead of columns
- Perfect for separating full names or product codes
Text Transformation Tricks
- Use Trim to remove leading and trailing spaces
- Clean eliminates non-printable characters
- Change case to Upper, Lower, or Proper for consistency
- Extract text before, after, or between delimiters
- Replace values to fix typos or standardize categories
- Add a conditional column for custom text rules
Date & Time Fixes
- Change data type to Date to ensure proper recognition
- Use the culture setting to fix day/month mix-ups
- Extract year, quarter, month, or day name for grouping
- Calculate age or duration using date subtraction
- Create a date table from a simple list of dates
- Fix invalid dates that would cause load errors
Filter & Replace Values
- Apply filters to remove blank or null entries
- Replace errors with a null or a default value
- Replace specific values across the entire column
- Use the fill feature to handle missing data
- Filter out irrelevant rows early to improve performance
- Preview changes immediately in the query editor
Apply & Refresh
- All steps are recorded in the APPLIED STEPS pane
- You can edit or delete any step at any time
- Changes are applied only when you click Close & Apply
- Your data model updates with the clean results
- Set up scheduled refresh to automate the cleaning
- Your reports now run on perfect, analysis-ready data