How to read the charts
Data doesn't lie. But it can confuse if you don't know how to read it.
Before you start
This guide helps you understand the charts you'll find in each myth.
You don't need to know maths. Just pay attention.
Each chart type tells a different story. Here we explain what to look for in each one.
Line chart
What it shows: How a value changes over time.
What to look for:
- If the line goes up, the value increases
- If the line goes down, the value decreases
- A flat line means the value doesn't change
- Sharp changes indicate important moments
Example: evolution of the foreign-born population 2002-2022
Bar chart
What it shows: Comparing values across different categories or countries.
What to look for:
- Taller bars = larger values
- Comparing heights tells you who has more or less
- Order is usually from highest to lowest (or vice versa)
- Look for where Spain sits in the ranking
Example: percentage of foreign-born population by European country
Donut chart
What it shows: How a total is split into parts.
What to look for:
- Each slice is a portion of the total
- Bigger slices = larger proportion
- All slices together add up to 100%
- Useful for seeing which part matters most
Example: housing distribution by type of use
Index chart
What it shows: Comparing trends starting from the same point (base 100).
What to look for:
- All lines start at 100 (base year)
- Values above 100 = grew since the start
- Values below 100 = fell since the start
- Compare the slopes, not the absolute values
Example: wages vs CPI normalised to 2008=100
Dual chart (two axes)
What it shows: Two different variables in the same chart.
What to look for:
- Each axis (left/right) measures something different
- Don't compare the numbers, compare the shapes
- Do they rise and fall together? There may be a relationship
- Do they move in opposite directions? There may be a conflict
Example: housing prices vs foreign-born population
Scatter chart
What it shows: Relationship between two variables. Each dot is one case.
What to look for:
- Each dot represents a country, region or year
- If dots form an upward line: positive relationship
- If they form a downward line: inverse relationship
- Scattered dots with no pattern: no clear relationship
Example: hours worked vs annual salary by country
Three rules for reading charts
- Read the title and axes. They tell you what each thing measures.
- Check the scale. A small change can look big if the scale is zoomed in.
- Find the source. It always appears below the chart. If there's no source, be sceptical.