What do you take from this chart?

• That you take the time to read. Title, axes, units, legend, period, footnote: errors almost always come from a misread axis or a percentage mistaken for a value.
• That you draw out a message. "Online sales went from 10 to 25" is a reading. "All the growth comes from the online channel, which is also the least profitable" is a conclusion.
• That you link it to the client's problem. A chart is never shown by chance: it is there to confirm or rule out a lead in your structure.
• That you spot what is missing. Saying which extra data would settle the matter shows you are already thinking about the next step.

1. 1

   Say out loud what the document shows

   One sentence: what is measured, over what period, in what unit. It gives you time to understand and avoids misreadings.
2. 2

   Look for what stands out

   The largest value, the biggest change, a break in trend, a segment moving against the others. Do a quick calculation if a ratio says more than the raw values.
3. 3

   Give the message, then what it implies

   One sentence for the conclusion, one for what it changes relative to your starting hypothesis.
4. 4

   Propose the next step

   The question this chart raises and the data you would ask for to answer it.

"I will take a few seconds to read it. This chart shows the client's revenue by sales channel over three years, in millions of euros, with each channel's margin shown underneath.

What I take from it is that all the growth comes from online sales. Stores are flat at around 80 million, while the online channel goes from 10 to 25 million. Yet its margin is half that of the stores. So the client is growing through its least profitable channel, which confirms the mix effect hypothesis I raised at the start and explains why the overall margin is falling despite higher sales. What the chart does not say is why the online channel is less profitable. So I would like to see its cost breakdown, delivery and returns in particular, to know whether that gap can be reduced."

This example is made up: it shows the tone and the construction, not a script to memorise. Your answer has to come from your own experience or from the data the interviewer gives you.

• Reading the figures one by one, left to right, without ever saying what they mean.
• Rushing and confusing percentages with values, or annual data with cumulative data.
• Commenting on the chart as a stand-alone exercise, without tying it to the case question.
• Trying to say everything. A chart usually carries one main message, sometimes two, and the interviewer expects you to find it.