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Choosing the Right Visual for Each Question

First lesson of the Designing Reports and Dashboards course, free to read: about 15 minutes, 3 exercises and 3 quiz questions. This is the catalogue's base lesson; in the student space, it is rewritten for your profile.

Objectives

  • Match a business question to a family of visuals
  • Avoid misleading or unreadable visuals
  • Build a first page with suitable visuals

Choosing a visualKey indicatorsChart readability

Start from the question, not the visual

The Visualizations pane offers dozens of visuals. It is tempting to pick the most spectacular one. The right approach is the opposite: state the reader’s question, then choose the visual that answers it fastest.

Question Family Recommended visuals
“Which store sells the most?” comparison bar chart, column chart (sorted)
“How are sales changing?” trend line chart, column chart by month
“What does revenue consist of?” composition stacked bars (100%), treemap, pie if 2 to 4 parts
“How are the amounts distributed?” distribution histogram by bins (groups of values)
“Does price influence quantity?” relationship scatter plot
“Where do we stand?” indicator card, KPI, gauge
“What are the details?” detail table, matrix

The essential visuals

  • Bar chart (horizontal): the best choice for comparing categories, especially with long labels. Sort by value.
  • Column chart (vertical): comparisons along an ordered axis (months, bins).
  • Line chart: continuous change over time; you can overlay actual and target.
  • Combo chart (lines and columns): for example sales as columns and attainment rate as a line on a secondary axis. Use sparingly: two axes make reading harder.
  • Card and KPI: one key figure, ideally with a trend or a target. The newer card visual can display several values and reference values.
  • Table / matrix: for detail and for readers who want precise numbers.
  • Maps: only if location adds information (proximity, zones); otherwise bars by region are easier to read.

Pitfalls to avoid

  1. Pie charts with too many slices: beyond 4 parts, the eye can no longer compare angles. Prefer bars.
  2. Truncated axis on a column chart: a bar starting at 120 instead of 0 exaggerates the differences. Bars must start at zero (a line, on the other hand, can have an adjusted axis).
  3. 3D, shadows, gradients: they distort proportions and add nothing.
  4. Too many colors: one color per bar for no reason is distracting. One neutral color and one accent color are often enough.
  5. Too many visuals: beyond 6 to 8 visuals per page, the message gets lost (and the report slows down).

Always include a reference

“415 € in sales”: is that good? Impossible to say without a point of comparison. Pair every indicator with a reference:

Taux d'atteinte = DIVIDE ( [Total ventes], [Total objectifs] )
Écart objectif = [Total ventes] - [Total objectifs]

A card showing “415 €” alongside “target 495 €, 83.8%” already tells a story: the chain is behind its targets. The Analytics pane (magnifying glass icon in the Visualizations pane) also adds reference lines (constant, average, median) to many visuals.

A simple approach

  1. List the reader’s 3 to 5 questions.
  2. For each one, choose the family, then the visual.
  3. Add the reference (target, prior year, average).
  4. Give the visual a title that answers the question (“Lille is the only store above 85% of its target”) rather than a descriptive title.

Exercises

Solutions and tests stay on the server. In the student space, your code is run and checked, and the tutor gives hints before the solution.

  1. TaskDifficulty 22 hints

    One question, one visual

    Starting model: the sales and targets star schema from the previous courses — FaitVentes (12 sales, Montant), FaitObjectifs (9 rows), DimMagasin, DimProduit, Dates (2026, sorted months), and the measures Total ventes = SUM ( FaitVentes[Montant] ), Total objectifs = SUM ( FaitObjectifs[Objectif] ), Taux d'atteinte = DIVIDE ( [Total ventes], [Total objectifs] ). If needed, rebuild it from these two files (C:\Formation\ventes_plat.csv and C:\Formation\objectifs_mensuels.csv):

    NumVente,Date,DateLivraison,CodeMagasin,Magasin,Region,CodeProduit,Produit,Categorie,Quantite,PrixUnitaire
V001,2026-01-03,2026-01-05,M1,Lyon,Auvergne-Rhône-Alpes,P01,Jus d'orange,Boissons,10,3
V002,2026-01-03,2026-01-06,M2,Lille,Hauts-de-France,P02,Pates,Epicerie,20,2
V003,2026-01-10,2026-01-12,M3,Nantes,Pays de la Loire,P03,Yaourt,Frais,30,1
V004,2026-01-17,2026-01-19,M1,Lyon,Auvergne-Rhône-Alpes,P04,Riz,Epicerie,15,2
V005,2026-01-24,2026-01-27,M2,Lille,Hauts-de-France,P05,Eau,Boissons,50,1
V006,2026-02-02,2026-02-04,M3,Nantes,Pays de la Loire,P01,Jus d'orange,Boissons,12,3
V007,2026-02-07,2026-02-09,M1,Lyon,Auvergne-Rhône-Alpes,P06,Fromage,Frais,8,6
V008,2026-02-14,2026-02-16,M2,Lille,Hauts-de-France,P03,Yaourt,Frais,25,1
V009,2026-02-21,2026-02-24,M3,Nantes,Pays de la Loire,P02,Pates,Epicerie,18,2
V010,2026-02-28,2026-03-03,M1,Lyon,Auvergne-Rhône-Alpes,P05,Eau,Boissons,40,1
V011,2026-03-06,2026-03-09,M2,Lille,Hauts-de-France,P04,Riz,Epicerie,10,2
V012,2026-03-13,2026-03-16,M3,Nantes,Pays de la Loire,P06,Fromage,Frais,5,6
    CodeMagasin,Mois,Objectif
M1,2026-01-01,60
M1,2026-02-01,70
M1,2026-03-01,50
M2,2026-01-01,55
M2,2026-02-01,60
M2,2026-03-01,40
M3,2026-01-01,50
M3,2026-02-01,65
M3,2026-03-01,45

    Build a Synthèse T1 page with:

    1. a Total ventes card and a Taux d’atteinte card;
    2. a sorted bar chart: Total ventes by Magasin;
    3. a clustered column chart by month with Total ventes and Total objectifs;
    4. a donut chart of sales by Catégorie (3 parts, acceptable);
    5. a visual title that states a finding for the bar chart.
    • The cards show 415 and 83.8%
    • The bars are sorted: Lyon 148, Lille 135, Nantes 132
    • The column chart shows January 180 / 165, February 185 / 195, March 50 / 135
    • The bar chart title is a finding (for example "Lyon leads, small gap between stores")

  2. Multiple choiceDifficulty 11 hint

    Change over time

    You need to show the monthly change in revenue over two years. Which visual should you choose?

    • Pie chart
    • Line chart
    • Gauge
    • Card

  3. Multiple choiceDifficulty 21 hint

    Truncated axis

    A column chart compares 132, 135 and 148 with an axis that starts at 130. What is the problem?

    • None
    • The gaps look huge when they are actually small
    • The bars are in the wrong order
    • The colors are wrong

End-of-lesson quiz

  1. Which visual is best suited to comparing 8 categories?

    • Pie chart
    • Sorted bar chart
    • Gauge

  2. Why accompany an indicator with a reference?

    • To fill the page
    • So the reader can judge whether the value is good or bad
    • Because Power BI requires it

  3. Where do you add an average line to a chart?

    • In the Analytics pane
    • In Power Query
    • In the Filters pane

The rest of the course

  1. Layout, Visual Hierarchy and Color20 min
  2. Interactivity and Navigation: Drill-Down, Drillthrough, Tooltips, Bookmarks20 min
  3. Conditional Formatting, Dynamic Titles and Field Parameters20 min
  4. Accessibility, Mobile Layout, Performance and Acceptance Testing15 min
Build my pathSee the full syllabus

Designing Reports and Dashboards · Intermediate · 1 h 30 min