1. Put people into CAC. Sales and marketing salaries, contractors and tools, all divided by new customers in the same period. A CAC built from ad spend alone is routinely under half the real figure — and you'll conclude the channel is a bargain and keep pouring money in.
2. Compute it per channel, never blended. A blended CAC is an average held down by your best channel. Split it and there's usually one or two channels losing money outright, which is exactly where the budget has been growing.
3. Use gross profit and the median for LTV. Revenue treats delivery cost as profit. The mean lets a handful of enormous accounts drag the number to a place no real customer occupies. The median is your typical customer.
4. Don't estimate retention from cohorts that haven't aged. If nobody has been a customer longer than three months, you cannot produce "average retention: 24 months" — that's an assumption wearing a number's clothes. Write it honestly: "extrapolated from current monthly churn, about 24 months, not yet observed."
Mechanism: these three numbers decide whether money can buy growth. Payback caps how fast you can spend — how long each unit of cash takes to come back. LTV over CAC decides whether the business is worth scaling at all. And the reason you need them rather than a feel for it is that sales happens to be exactly the kind of environment intuition cannot learn.
Honest boundary: with only a few dozen customers, LTV is largely fiction — the retention curve hasn't grown yet, so you're multiplying your own assumption by a big number. Watch payback and per-deal gross profit instead; they're enough. And all three answer whether the business scales, not whether this deal is worth chasing. That second question belongs to qualification, and no financial ratio will decide it for you.
1. Ask how many deals the claim would need, before you make it. If you can't compute it, use the diagram's orders of magnitude: a few dozen shows direction and never a decimal point; hundreds are where comparisons begin. This one habit kills half your bad decisions.
2. When volume is short, move upstream to process metrics. Closing is the sparsest layer, so it's the noisiest. One layer up: meetings booked, second-meeting rate, share of deals where you reached the decision-maker, reply rate within seven days of a quote. Ten times the volume, far less noise, and they happen earlier, so a change shows up sooner.
3. Fix the definition and the window before you look. Whether you count by the month a lead entered or the month it closed has to be settled in advance. Choosing the window after seeing the result can make anything look effective — that isn't analysis, it's telling yourself a story.
What to say in the weekly meeting: "Is that lift real or is it noise? How many deals did we have this month — enough to see a difference that size?"
Mechanism: a close rate is a proportion estimated from a string of won/lost draws, and the smaller the sample the more it jitters. The jitter carries no information — but people reliably supply a cause for it, preferably whatever they did most recently.
Boundary: a small sample isn't no information. A buyer's own words in a loss, or the same obstacle recurring, is qualitative signal worth having after a handful of cases — you can't build a percentage on it, but it tells you what to change next. The real error is turning five deals into a percentage and rebuilding the process around it.
1. Count by rung: how many deals sat in each of the five, and how many closed. A dozen deals per rung is enough for the shape to show.
2. Look for two biases: probability — if every rung came in below its label, you're systematically optimistic, so discount as the diagram shows; dates — take the median number of days by which real close dates ran late, and add it to every future date from now on. Nearly everyone has both, and fixing them costs nothing.
3. Always report two numbers, never one blend: the commit is the 90% rung only, what you'll stand behind; the forecast is every rung weighted by your calibrated probabilities. Asked how the quarter looks: "Commit is 800k, forecast 1.3m, and historically my forecast runs about ten percent optimistic."
What changing a probability sounds like: "He brought finance into the call today — that's new information, so this moves from 50% to 70%." Without a sentence like that, a change is just a mood.
Mechanism: learning runs on the gap between what you expected and what happened. If the expectation was never fixed as a number, your brain rewrites it after the fact to match the outcome, the gap collapses to zero, nothing looks like a mistake — and nothing is learned. Writing it down exists only to keep the error alive.
Boundary: no more than five rungs — a 17% carries only the appearance of precision. More important: never tie forecasts to compensation. Once the number you report determines your reward, what gets reported stops being what you believe and becomes what is safe. It's the same logic as commission: whatever you measure, you get the performance of it. If you need both, keep the commit and the forecast separate and hold people to the commit only.
Ask the buyer (one email is enough — no defending, no re-pitching, you're here to learn):
1. "Which two options were you finally choosing between?" — this asks about the alternative, not for a reason.
2. "At the moment you decided, what was the one thing that settled it?" — asking about that moment is far more honest than asking why they didn't pick you.
3. "Which part of dealing with us took the most effort?" — this one most often surfaces something you can actually fix.
Internal rule one: read the next step and the probability recorded at the time before the discussion starts. Reverse that order and the meeting becomes an exercise in constructing a plausible account of a known result.
Internal rule two: each quarter, run a pre-mortem on two or three live deals — "assume this is dead in three months; everyone write the most likely cause." The same cause tends to keep appearing: nobody ever met the person who actually decides.
Mechanism: once the outcome is known it reaches backwards and rewrites your memory of what you believed, so a review slides from examining a decision into assembling evidence for a conclusion you already have. Discipline doesn't fix this. A contemporaneous record does — it's the only thing the outcome can't edit.
Boundary: discount what loss interviews tell you — buyers offer a presentable reason, and "budget" is the easiest shield to reach for. That's why you ask about alternatives and process rather than "why didn't you choose us". And a review stops working the moment it affects anyone's rating: people will only bring the version that survives scrutiny. If you want reviews to be useful, telling the truth has to be safe in that room.
Sixty minutes to replace a feeling with four checkable numbers.