Every agency I have watched lose an account lost it the same way: nobody wrote down the date on which the
question would be answered, so month six arrived as a surprise instead of a read-out.
The reason is arithmetic, not effort.
Each client is a separate funnel
Traffic does not merge across clients. Ten clients with 2,000 contacts a month each is 20,000 contacts a month
and not one test — it is ten tests, because the audiences have nothing to do with each other. A floor computed
for one funnel says nothing about the roster.
The floor is the same one every honest test uses: a 3% base rate, a +20% relative lift, 80% power, alpha
0.05 → 13,914 contacts per arm, 27,828 in total.
Put the roster in
A client producing 2,000 contacts a month puts 1,000 in one arm. 13,914 ÷ 1,000 is 14 months to the floor.
- 6,000 contacts a month → 5 months
- 12,000 contacts a month → 3 months
- 2,000 contacts a month → 14 months
None of that changes because you work harder. It changes when the client's volume changes — so the honest
deliverable for a small client is a diagnostic, and the honest deliverable for a big one is a date.
Flip it into a sales rule: the smallest volume readable inside the horizon you are willing to sell is 27,828 ÷
horizon. A 6-month promise needs 4,638 contacts a month; a 3-month promise needs 9,276. Below that line, sell
definitions, instrumentation and a stop rule, and put the test on next year's calendar.
Four lines to write before the first invoice
- Which clients can fund a verdict at all. Check each client's monthly volume against 4,638 (6 months) or 9,276 (3 months). Say it out loud at the pitch, not in month nine.
- The one unit you will be judged on, per client. One number per client, named in the agreement. When the unit is "whatever moved", you are being measured on the client's best week.
- The read-out date in the contract, not in the deck. A promise with a date can be planned around. A promise without one gets renegotiated monthly — usually in the client's favour, usually in month three.
- Who owns the number on the client's side. One name. Without it, the read-out is decided by whoever is most uncomfortable in the room.
The retainer changes shape
An activity report answers "what did you do". A calendar of floors and dates answers "when will we know", which is
the question that actually decides a renewal. Clients run in parallel; two tests inside one client do not — they
split one arm's volume and turn both into documentation.
Tools that do the arithmetic for you, free and without signup:
- Agency capacity planner — https://axelfreeman.github.io/marketing-mindset/tools/agency-capacity-planner.html
- Channel verdict fit — https://axelfreeman.github.io/marketing-mindset/tools/channel-verdict-fit.html
- Same maths as a CLI —
npx marketing-mindset sample --base 0.03 --lift 0.2
Related: marketing engineer for agencies and the
public packages — $900 Sprint, $1,900/month Engine, $2,900 Full Build — written up at
https://axelfreeman.com/marketing-engineer.html
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