Marketing Wisdom: an evidence library that answers back

Mark Ritson has spent years testing marketers on the basics, and the results are consistently humbling: only about 45% of marketers can correctly define penetration. Yes, I know - shame on us marketers.

Shame...

This explains a lot about marketing meetings. An industry that quotes Byron Sharp the way other industries quote regulations is, apparently, quoting from memory. The evidence exists - it is just buried in 90-page PDFs nobody opens twice, conference talks that evaporate after the applause, and podcasts you half-listened to on a run.

So we built the library we kept wishing existed. It is called Marketing Wisdom, and as of this week it is accessible for all Selfstormers.

What is actually in it

800+ findings, each one attributed down to the page. All of them are individual pieces of evidence: a stat with its chart, a principle with its author, a quote with its author and year, a trend with its expiry date (more on that below). Every finding has its own page you can link in a deck, a document or an argument you are currently winning.

The library covers the whole job, organised into topics you can browse straight through:

• Brand Strategy (396) - penetration, mental availability, the 95/5 rule, ESOV, category entry points

• Brand & Creativity (184) - why consistent brands compound and dull ones pay a media tax

• Paid Media (111) - what ad spend actually buys, and when it stops buying it

• Trends (59) - dated, curated, and honest about their shelf life

• AI (54), Creative Strategy (52), Content & Social (34) and Growth (13)

Two kinds of knowledge live side by side, deliberately. Evergreen evidence - including all 61 marketing laws, woven directly into the wall - and curated trend evidence that carries a visible date and an expiry plan. A 2026 forecast should not be quoted in 2028 as if it were physics, so in this library it simply will not be: dated packs get flagged, superseded ones point to the newer edition.

Ask Wisdom: the part that changes how you use it

Libraries are where good intentions go to scroll. So the front door is not a filter - it is a question box.

Type a marketing question into Ask Wisdom and you get a distilled answer with the sources linked underneath. The answer is built only from the evidence in the library - which means every claim in it can be clicked, checked and quoted.

Five things worth asking it before your next planning meeting:

• "Does emotional advertising actually outperform rational?"

• "What do celebrities in ads really deliver?"

• "Is the 60/40 brand vs performance split still true?"

• "What does brand consistency pay, in numbers?"

• "How is AI search changing the way people find brands?"

This is, as far as we know, the first time marketing''s scattered wisdom - stats, laws, principles and trends - sits in one place and answers back. Not the average of the internet. The cited part of it.

Whose evidence it is

The names you argue with and the institutes you cite: Byron Sharp, Mark Ritson, Les Binet and Peter Field, Paul Feldwick, James Hurman... - alongside Kantar, System1, WARC, the IPA, Ehrenberg-Bass, Meta, Google, dentsu, VML and others. Plus ofc the people who got there first: Ogilvy, Bernbach, Hegarty, Gossage.

And one thing we have not seen anywhere else: the library is mined from talks and podcasts, not just reports. When Sharp and Ritson spend two hours disagreeing on Uncensored CMO, the ten claims worth keeping end up here - timestamped, attributed, checkable. Same for The WARC Podcast, Cannes stages and conference sessions that would otherwise live and die as a LinkedIn carousel. That 45% penetration stat above? A podcast, minute 36. Now it has a page.

Take it, it is yours

Every finding is built to leave the library. One click exports a bite to a PowerPoint slide - headline, chart, citation, done - because the real destination of a marketing stat is slide 14 of somebody''s deck. And every finding has a share link with a proper preview card, so the next argument you settle in Slack can be settled with a URL instead of "I read somewhere that...".

The wall''s first page and every individual finding are open to everyone. The full library - search, topics, filters, exports - is part of Pro, and unlike every other paid library out there, this one grows every week as we mine new reports and talks.

Go ask Wisdom something you are sure you already know. Worst case, you are in the 45%.