The KPI Legend That Nobody Reads (Because We Put It in the Appendix)
We hide the definitions of our metrics on page 50 and then wonder why the client is confused. If a chart needs a legend, put it next to the chart.
The Mystery of “Engagement Rate”
I watched a debate unfold between a client and a consultant that was entirely avoidable. They were arguing about “Engagement Rate.”
To the consultant, “Engagement Rate” meant clicks plus likes divided by impressions. To the client, “Engagement Rate” meant how many people replied to the email.
They spoke past each other for ten minutes. The client was getting frustrated. “Why is the engagement so high if nobody replied?” he asked, looking at a bar chart that showed a healthy 5%.
The definition of the metric was in the report. It was on slide 52, in a section titled “Appendix C: Methodology and Definitions.”
It was tragic. We expected the client to pause the meeting, scroll down 40 pages, memorize a formula, scroll back up, and then interpret the chart. That is too clever by half. That is not user experience; that is a treasure hunt.
The Confusion: The “Appendix” Fallacy
We use the Appendix as a dumping ground. It is where we put the things we know are important but can’t be bothered to design properly.
We think, “Well, it’s in the document, so I am covered.” This is a liability mindset. You are covering your own backside, not helping the client.
When a client looks at a chart, their working memory is limited. If they encounter a term like “Share of Voice” or “Attribution Window,” and they don’t instantly recall the definition, they will either:
- Guess (and often guess wrong).
- Tune out.
- Ask a question that makes them feel stupid.
None of these are good outcomes.
The Headline: Just-In-Time Education
The fix is simple: Contextual Definitions.
If you use a complex metric, define it right there. On the slide. Next to the chart.
You don’t need a paragraph. A simple subtitle works wonders.
- Bad: Header: Q3 ROAS Performance
- Good: Header: Q3 ROAS Performance Subtitle: (Return on Ad Spend: Revenue generated for every £1 spent)
[TO EDITOR: Before/After comparison text block. Top block (Before): A chart titled “Weighted VTR by Quarter” with no explanation. Bottom block (After): The same chart, but under the title is a small grey caption: “Note: VTR (View Through Rate) measures users who watched >50% of the video.”]
Suddenly, the client is sorted. They don’t have to guess. They don’t have to feel embarrassed about asking. The answer is right in front of their nose.
It also keeps us honest. If you can’t define the metric in one sentence under the title, it is probably too complicated to be in the report in the first place.
Stop hiding the instructions in the basement. Put the sign on the door. It’s just manners.
FAQs
But won't defining terms on the slide make it cluttered?
A little text is better than a lot of confusion. You can use footnotes or subtitles. Just don't make them turn the page.
My client has been with us for years, surely they know the terms?
Never assume. Clients change roles, get tired, or forget. Reminding them is politeness, not an insult.
Can't I just use a tooltip?
If it's a live dashboard, yes. But if it's a PDF or a slide, tooltips don't exist. You need ink.