ETF5922 Chap.2 Power BI Foundations
Power BI Foundations
Filters define the number
Power BI appears in the published teaching sequence as an introductory visualisation tool. Field types affect ordering, aggregation and the visual forms available to a report.
Relationships propagate selections
A measure is evaluated under active filter context, while a stored column retains row-level values.
Slicer state should remain visible when a report is exported or discussed outside the interactive page.
Reconcile cards with source rows
A visible slicer tells the reader which subset produced every card and chart.
Without that state, two viewers can read different totals from the same report and neither can reconstruct the comparison.
Reconcile cards with source rows in context
Model design precedes report design because relationships and grain decide which totals are possible. A region slicer should propagate through a controlled relationship into sales rows, and a measure should recalculate within that context.
Unexpected totals can arise from duplicate keys, bidirectional paths or implicit aggregation even when the chart appears polished. An audit therefore begins with a small table and manually verified sums, proceeds through each filter state, and ends with titles that expose the selection.
Static exports are especially revealing: if the chosen subset cannot be recovered after controls disappear, the dashboard has not fully communicated its analytical state.
What this chapter covers
- 01
Power BI appears in the published teaching sequence as an introductory visualisation tool.
- 02
Field types affect ordering, aggregation and the visual forms available to a report.
- 03
A measure is evaluated under active filter context, while a stored column retains row-level values.
- 04
Slicer state should remain visible when a report is exported or discussed outside the interactive page.
- 05
Use field and relationship to frame the reader's task
- 06
Check measure against column before styling
- 07
Explain how model changes the visible comparison
- 08
Audit slicer without removing necessary context
Reconcile a card with filter context
- 2Resolve the active scope before adding the visible values.
- 1Compare the filtered result with the full total so the missing share is explicit.
- 3Place the filter state beside the headline measure rather than leaving it in a hidden control.
- 2Describe the result as conditional on the retained regions.
Key terms
- Filter context
- The complete set of report, page and visual filters governing a displayed calculation.
- Relationship
- A model connection that determines how a selection in one table propagates to another.
- Measure
- A reusable calculation evaluated under the current report context rather than a fixed stored number.
- Slicer
- A visible control through which a reader selects the subset shown by coordinated visuals.
Power BI Foundations FAQ
Why must a dashboard show an active slicer?
A visible slicer tells the reader which subset produced every card and chart. Without that state, two viewers can read different totals from the same report and neither can reconstruct the comparison.
How do I audit a Power BI total?
Write the expected rows and sum before reading the card, then inspect slicers, visual filters, relationships and aggregation. Clear and reapply the selection while checking that cards, tables and titles change together. A number is validated only when its filter path and contributing records reconcile.
When is a measure preferable to a stored column?
Use a measure when the result should be evaluated under changing report context, such as sales for the currently selected regions. A stored column is calculated row by row and does not automatically represent a contextual aggregate. The choice should follow the analytical role, not interface convenience.
How should a static dashboard export communicate scope?
It should print the selected regions or date range beside the headline measure, because the interactive control may be absent or cropped. A dynamic title, subtitle or annotation can preserve state. The exported table and cards should also reconcile under that same selection so the page remains auditable away from the live report.
Exam move
Build a two-table model with one deliberately duplicated key. Predict the card total, inspect the relationship, and compare the result before and after a slicer selection. Then repair the key problem and annotate the active context beside the measure. This drill links Power BI behaviour to row-level evidence instead of treating the interface as a list of buttons.
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