Sources and provenance

#How to read this lesson

Every material claim across this course already carries an inline [Established], [Directional], or [Speculative] tag where it's made — see the confidence-tag system in How to use this course. This lesson collects the underlying sources behind those tags in one place, organized by tier, the same structure SMMA and Ad Agency use for their own reference lessons.

A note on this course's research environment, worth stating once rather than per-claim. "Marketing agency" and "fractional CMO" content online is dominated by a recognizable cluster of financial-modeling, business-plan-template, and lead-generation sites that produce near-identical, suspiciously precise figures for nearly every business type they cover — the same pattern Marketing's own start-here lesson names for "2026 benchmark" content generally. This course encountered it more aggressively than most sibling courses, including two claims falsely attributed to McKinsey and Harvard Business Review specifically, checked and discarded below rather than repeated.

#Established — primary sources, directly checkable

• US Bureau of Labor Statistics and IBISWorld's published industry-count data — the ~114,000 US advertising/marketing-agency business count and its year-over-year growth rate, used for market-context orientation. IBISWorld is a named, paid industry-research firm with a long track record; this research accessed its published headline figures rather than a full underlying report, so treat the count as reliable and any deeper IBISWorld-attributed detail elsewhere in agency-industry content with more caution unless independently corroborated.
• Federal Trade Commission, general advertising-truthfulness standard (claims must be truthful, non-deceptive, and evidence-based) and 2026 endorsement-disclosure enforcement focus, including the brand-agency joint-liability principle for influencer/creator content — the same regulatory floor SMMA covers for its own compliance lesson, relevant here because this course's agency thread frequently produces exactly this kind of client-facing content.
• David C. Baker and Blair Enns, own published books and public work (The Business of Expertise; The Win Without Pitching Manifesto) — primary-source practitioner frameworks, not secondhand summaries, for the positioning, pricing, and execution-boundary material in How fractional CMO engagements get sold and Where advisory-only fails. Both are named, decades-track-record practitioner-authorities specifically on expert-advisory business models — see the source-tiering discussion in that lesson for why they're treated as more reliable than typical fractional-CMO marketing content.

#Directional — disclosed-operator data or a consistent independent pattern

• Multiple independent 2026 agency-pricing and fractional-CMO-pricing guides — the retainer and hourly-rate ranges throughout Modules 3 and 4 (agency retainers $2,500–$30,000+/month by tier; fractional CMO $5,000–$25,000/month and $200–$500/hour; general consulting $50–$500+/hour). No single source discloses a full survey methodology; the ranges are consistent enough across independent sources to treat as real planning inputs, not precise quotable figures.
• Frak Conference, State of Fractional Industry Report 2024 — the 60,000-to-120,000 fractional-leadership-workforce growth figure in The fractional CMO model and market rates. A named, dated industry-association report, accessed through secondary citation rather than the primary report directly; the association has some structural incentive to report its own adjacent market favorably.
• A single 2026 industry-benchmark source on scope creep — the 57%-of-agencies-losing-$1,000–$5,000/month and 99%-of-agencies-absorbing-unbilled-work figures used in both Where advisory-only fails and Failure modes. No disclosed sampling methodology; internally consistent with the broader, well-attested pattern that scope creep is a chronic industry problem.
• Agency Management Institute's 55:25:20 benchmark ratio — a real, long-standing, named agency consultancy's operating-margin target, cited in Why businesses buy outside marketing help, accessed through secondary citation rather than AMI's own primary materials directly.
• Multiple independent 2026 agency-profitability benchmark sources — the narrower-scope-agencies-post-higher-margins pattern (roughly 30% net margin for narrowed-scope agencies vs. ~13% industry average, and margin compression from ~19% at under-10-employee agencies to ~8% at 50+ employees), and the ~$163,000-revenue-per-employee benchmark. No single disclosed-methodology study; direction treated as reliable, specific percentages as planning ranges.
• A single 2026 client-churn survey source — the weak-strategic-guidance (~68%), poor-communication (~57%), and price (~37%) churn-reason figures, and a separate source's ~48%-delivery-dissatisfaction 2026 figure, both in Failure modes. No disclosed sampling methodology.
• A single 2026 cold-email-benchmark source — the cost-per-meeting ($150–$300) and conversion-rate figures in Client acquisition and pricing models, and a separate large-sample reply-rate baseline (~3.4% across 100M+ sends, per Instantly's own platform data — a real, disclosed-volume, though vendor-self-reported, figure).
• Multiple independent agency-industry startup-cost breakdowns (excluding the discarded cluster below) — the $2,000–$60,000+ capital tiers in Team and capital requirements, reasoned consistently with SMMA's and Ad Agency's own sourced capital tiers for comparable line items (LLC formation, insurance, software).

#Speculative — single-source, unsourced, or actively discarded

• A claim attributed to McKinsey that fractional leadership cuts executive compensation costs by 40–70%. Checked directly against mckinsey.com; no matching publication found. Repeated across dozens of fractional-executive marketing pages with no working citation to an actual McKinsey report anywhere in the search results this research reviewed. Discarded — named in The fractional CMO model and market rates specifically so it isn't repeated as fact by anyone using this course.
• A claim attributed to Harvard Business Review that companies using fractional CMOs average 29% revenue growth versus 19% without. Checked directly against hbr.org; no matching study found. Widely repeated across fractional-CMO marketing content with HBR cited as the source and no working link to an actual HBR article. Discarded — same treatment as the McKinsey figure above, and the same pattern this platform's SMMA and AI Agency reference lessons each name for their own untraceable, prestige-laundered statistics.
• A financial-modeling-vendor figure claiming $115,000 in one-time setup costs and roughly $908,000 in total capital to start "a marketing agency." No disclosed client profile, team size, or scenario assumptions behind either number. Part of a recognizable cluster of near-identical AI-generated-looking "startup cost" articles that publish the same suspiciously precise cost breakdown for nearly every business type. Discarded — named in Team and capital requirements as the same category of outlier scenario Ad Agency's own capital lesson catches in a different vendor's $415,000-CAPEX figure.
• A single market-research-firm estimate of the global fractional-executive market at ~$9.4 billion in 2025. No disclosed methodology this research could verify independently. Used only as rough scale context in The fractional CMO model and market rates, not as a number to plan against.
• A single frequently-cited fractional-CMO case study (conversion rate 11.4% → 24.2%, cost-per-sale dropping proportionally) in How fractional CMO engagements get sold — cited only as an illustration of the kind of specific, attributable proof that functions as real sales evidence, not as a typical or expected outcome for any given engagement.

#What this list is not

This is not a claim that every Directional or Speculative source above was independently re-derived from underlying data — that's precisely what those tiers mean: this course could not verify them further, and says so rather than dressing up a blog post or an unattributable "McKinsey says" line as settled fact. Where this course says [Established], the claim was checked against a primary source directly — including, in two specific cases, checking a famous-sounding attribution against the named organization's own site and finding nothing there. Everywhere else, treat the number as a planning input to re-verify against your own market, your own quotes, and your own client conversations — not a figure to repeat to a prospect, a lender, or in your own marketing.