How your category's growth rate and buyer journey length change who's actually in-market, and what that means for your budget.
The 95:5 rule says 95% of B2B buyers are out-of-market at any given moment. Ehrenberg-Bass developed it for stationary markets: stable categories where the pool of potential buyers doesn't change much year to year.
Dale Harrison showed what happens when it does. In growing categories, first-time buyers flood the in-market pool continuously. They don't have vendor preferences yet. They aren't on your retargeting list. And their share of the in-market pool grows as the category grows faster.
But the in-market pool isn't one thing. Kerry Cunningham's research on B2B buying stages shows that most buyers in evaluation are in the Awareness and Consideration stages. They haven't run a search query yet. Performance marketing can't find them. This pre-search window is the dead zone: real buying momentum, invisible to your tools.
The longer the buying journey in your category, the larger the dead zone. A 3-month journey has almost none. A 12-month journey means three-quarters of all buyers in evaluation may never show up in your intent data.
Set the four inputs for your category.
Growth rate model by Dale Harrison: "Category Growth Breaks the 95:5 Rule" (LinkedIn, 2026). Buying stage framework by Kerry Cunningham (6sense B2B Science Series). Introduced in Open Folders: How markets actually grow →
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Active search (Decision + Purchase stages): Harrison's formula derives the quarterly flow of buyers entering active vendor evaluation. active = (25 / cycle) + ((1 + growth/100)^0.25 − 1) × 100. The baseline (25 / cycle) reflects purchase frequency: at a 5-year buying cycle, 25/5 = 5% of buyers are in active search at any moment, matching the original 95:5 rule. Shorter cycles raise the baseline; longer cycles lower it. Verified against Harrison's published data points: CRM at 13.4% growth → 8.2% active ✓; 100% growth → 24% active ✓.
Dead zone (Awareness + Consideration stages): Buyers who are researching but haven't started active vendor outreach or run a search query. When buying journeys exceed one quarter (3 months), buyers from prior quarters are still mid-journey, building a shortlist, without yet triggering any intent signal. deadZone = active × max(0, journeyMonths/3 − 1). At a 3-month journey, dead zone = 0. At a 9-month journey, dead zone = 2× the active search pool. At a 12-month journey, dead zone = 3× the active search pool.
Total evaluating: totalEvaluating = active × max(1, journeyMonths/3). Every buyer in any stage of evaluation right now: dead zone plus active search.
Stage mapping: The five buying stages (Target, Awareness, Consideration, Decision, Purchase) map directly to formula outputs. Target = out-of-market (100% − total evaluating). Awareness = first third of the dead zone. Consideration = remaining two-thirds of the dead zone. Decision = first half of active search. Purchase = second half of active search. This mapping is consistent with Kerry Cunningham's B2B buying stage research (6sense Science Series).
First-time buyers: New category entrants as a share of the active search pool. At 0% growth, all active buyers are replacement buyers. As growth rises, first-time entrants dominate. The buying cycle shifts the ratio: shorter cycles mean more replacement buyers relative to first-timers. The ratio holds across the dead zone and active search alike.
Budget reach: Performance marketing reaches active-search buyers (Decision and Purchase stages). Brand reaches dead zone buyers (those forming preferences before they search) plus the next wave of active buyers entering the market. perfReach = min(P×2, 1) × active. brandReach = min(B×2, 1) × min(deadZone + active, 1). Peak total reach occurs at a 50/50 split, where both pools are fully covered. As journey length grows, so does the dead zone. A heavy performance weighting reaches a shrinking share of the buyers who are actually deciding.
This model was introduced in Open Folders, a weekly newsletter on marketing science, measurement, and the gap between what the research shows and what teams actually do.