The EVIDENCE stack — how to show what you say_ make a powerful point-01

The Evidence Stack — How To Show What You Say

Have you heard the joke about the tractor salesman and the farmer? No? Here goes. A tractor salesman visits a farmer and asks to demonstrate his new tractor. “Sure, go on then,” replies the farmer. The salesman jumps in, plows three fields, pulls stubborn tree-stumps and bales a ton of hay, all in record time. “Well, what do you think?” asks the salesman, jumping off the tractor. The farmer replies, “Sure, it’s all very well in practice, but what’s it like in theory?”*

Like most of my jokes, I inherited this one from my father. It’s not necessarily funny, but it makes a point.

When you’re presenting, pitching, or selling tractors, every slide should have a point.   Michael Alley’s Assertion-Evidence model is a proven technique to put that point across on a slide. His research found that a compelling, crisp headline in sentence form, backed up by evidence (usually visual) in the main body of a slide, increases comprehension and recall. This brings us to the question – is some evidence better than others? What type of evidence works best to build credibility? How do you show proof?

The evidence stack is the brainchild of Simon Levin and Joel Wecksell. Both former Gartner analysts, they now advise technology companies on how to position their products to advisory firms like Gartner and Forrester.

“Analysts are taught to never assess a company by what they say they are doing, or what they say they will do, but by proof of what they are doing and proof of what they have done. That’s where the layers of evidence come in,” Says Levin. It’s the distinction between claim and proof that’s important, and how credible the evidence is along the way.

Let’s look at the stack — from bottom (weakest) to top (strongest).

The Claim, with a little Hyperbole

This is the bottom of the stack. It’s the assertion part of Alley’s Assertion-Evidence model. On a slide it could be the headline. On a web landing page, it might be the central strap line. They are unsubstantiated, usually not much better than “now with 50% more magical ingredients!” But it’s important to make a claim. In fact, it’s essential, just be aware that you need to add evidence. For example,’s “Conference Calls as easy as tying your shoes” or UberConference’s “The Best Conference Call System In The World. Ever.” Both set out very clearly what they’re about. But can they both be right? After the claim, we have to start to add evidence, and as you will see, the more concrete and visceral the evidence is, the better. The more you can show evidence, the better a presenter you will be.

Blinding with Science

Unfortunately, this is the default setting of a lot of marketers, and a lot of decks are stuffed with techno-babble, acronyms and terms of art. If we’ve made a claim, say Super Skin Cream, watch fine lines and wrinkles vanish overnight, to blind with science we now need to add a smidgen of jargon and a touch of mumbo-jumbo. Just enough to sound impressive, but to the discerning observer, not really convincing. Super Skin Cream, now with Retijuve™ and organic Acacia Extract, watch fine lines and wrinkles vanish overnight. You will see decks stuffed with this, giving the presenter the warm and fuzzy feeling that there’s actually useful information in there. For example, the assertion might be, a complete set of infrastructure and application services that enable you to run virtually everything in the cloud, and the evidence you give to back that up would be an architecture diagram with terms like 3-tier service oriented architecture. Throw in enterprise-grade, edge nodes and leverage multiple IP addresses to implement a virtual IP (VIP) address high availability failover solution and my head starts to spin.

Demonstrate Know-How

Albert Einstein famously said, “If you can’t explain it simply, you don’t understand it well enough.” That’s a lesson that has been firmly renounced in business. Blinding people with science and marketing hyperbole are standard ways of speaking. It’s the language of the tribe. Thankfully, speaking simply and demonstrating know-how seem to be on the rise. It’s the reason behind the growth of Corporate Storytelling, Infographics and Explainer Videos. Companies like Dropbox, and Crazy Egg have made good use of them in explaining their products and building their brands. There seems to be a human reaction to simple explanations. Simply put, we’re more likely to believe them. In recent research, Occam’s razor  — the simpler explanation is the better one —  is proving out psychologically. We have a cognitive bias to prefer simpler, more common sense explanations.

Credibility, Bought and Borrowed

Moving up the stack we come to the idea of using other’s credibility, and bathing in its halo. Let’s assume you’ve made your claim, have a few choice words to describe it, and you’re keeping the techno-babble in your back pocket for later. You can explain your point simply, in a way that would make Einstein proud and Occam jealous. You’re still stuck in the realm of theory, and have no proof. What to do? In absence of hard proof, borrow some credibility. When Saab was first introduced in the US, being from Sweden wasn’t enough to convince you it was a vehicle equipped for difficult snow-bound winters. Being the vehicle of choice for the Aspen police force did. Nike had been in the golf business since 1984, but it wasn’t until it bought some credibility from Tiger Woods in 1996 that the business took off. Off course, the best endorsement of your assertion is the one from your customer. The more credible (the customer and the statement) the better.

Mapping Data

Further up the stack still, we begin to get to real evidence, in the form of data. Of course, not all data is created equally, and certainly not displayed equally. First, it has to be relevant Data. Much can be implied from a single data point, which can be good for the presenter. Although as an audience member, anchoring to that single data point may be unwise. Projections are also a little dodgy, but look very convincing. They’re almost always predictions of the future,** and despite an exhaustive search of the Internet, I have found no-one that can credibly help me with my Powerball picks. If you were an honest presenter of data, you would at least put the hockey stick curve where the future is bright in a dashed line, indicating that it’s your, (or some other more credible sources) best guess. If you’re going to use data to show evidence, use real data and tell a story.

Demonstrate and Use.

Back to the tractor, the very best way to back up your assertion is proof that it works. Putting something in people’s hands, giving them a real experience, is the best source of evidence. It makes it real, and it makes what you’re talking about come alive. Steve Jobs, presentation god, was the master of the demo, to the point that Apple’s stock rose after each one. Although even he had the occasional problem. This may be in the form of a canned demonstration, (less plausible) to a full trial (more plausible). Don’t underestimate the power of touch. It’s defined retail experience  since the days of Harry Selfridge.  Look at what the Apple store has done to change shopping experiences. Being able to touch and play with stuff makes it feel more valuable. A recent study showed the longer you touch an object, the greater the value you assign to it. Best of all perhaps, real customers showing how they use real products, and talking simply and glowingly about them.

The Evidence Stack.***

Evidence Stack Infographic

Make the claim, and then go as high up the stack as you can.

*For best results with this joke, the farmer needs a thick accent of your choice.

**Unless you manage to find an old one to laugh at.

***Note that the Evidence Stack, adapted from Levin and Wecksell’s Four Layers of Evidence differs slightly. In the Levin-Wecksell model, designed to communicate with analysts, “demonstrate and use isn’t the top of the stack – it’s one rung down. demonstrating the tractor at the manufacturers offices has way less value than the farmer next door telling me he has that tractor and it does the job perfectly. Customers are top of the stack and everything to do with them – case studies, interviews etc.”

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Gavin_Animated-GifGavin is a founding partner at fassforward consulting group. He blogs about PowerPoint, Presenting, Communication and Message Discipline at You can follow him on twitter @powerfulpoint.

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  1. David Prandi Chevalier | July 10, 2013 at 9:05 am

    Thank you for sharing!!!
    I find it very very very useful.
    Good luck.

  2. Peter | July 12, 2013 at 11:00 am

    Those police cars in Aspen are a great example of Argumentum a Fortiori…. the “Mikey Likes It” structure; if they are tough enough for snowy cops, then they’re tough enough for you.

  3. The Contractor | August 15, 2013 at 1:55 am

    Right on point. With regard to the glut of babble … numbers don’t lie, people do.

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