Power BI
Common DAX Mistakes That Break Business Reports
The DAX mistakes that create wrong totals, blanks, slow reports, and confusing business logic.
A measure looks correct in one visual and wrong in another. Totals do not add up. A filter changes something unexpectedly. This is often a context problem, not a Power BI bug.
DAX is powerful because measures respond to filter context. It is also easy to misuse when the model grain, relationships, or business definition is unclear.
The practical context
Use DAX measures to express reusable business logic over a clean model.
Complex DAX can hide modelling problems and create silent errors.
The model author owns measure definitions and validation evidence.
Measures that are readable, tested, and trusted.
How to approach it
A useful approach is deliberately simple. Start with the business question, make the data and ownership visible, then add technical detail only where it improves reliability or action.
- Start with a simple base measure before writing complex logic.
- Check the grain of the table used in the calculation.
- Use measures for aggregations rather than calculated columns where possible.
- Validate totals against a small sample.
- Document business definitions beside important measures.
Common mistakes
Using calculated columns for values that should be measures.
Forgetting that totals are recalculated, not just summed rows.
Using ALL or REMOVEFILTERS without understanding the effect.
Testing only one slicer combination.
A simple example
A margin percentage should usually be total margin divided by total revenue, not an average of row-level percentages. The second version often produces wrong totals.
Most DAX problems become easier once the business definition and model grain are clear.
Checks before you move on
The audience can explain what the output means without the analyst in the room.
The data source, calculation logic, refresh, and access model have owners.
There is a clear path for questions, exceptions, and corrections.
Success is measured by better decisions or less manual effort, not page views alone.
Key takeaway
Better DAX starts with a better model and a clearer business question.
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