PromptSharp › Daily briefs › Marketing › September 25, 2026

Marketing prompt of the day

September 25, 2026 · for Brand and growth marketers, agency strategists, content leads. One sharp, copy-paste prompt — free, every weekday.

You are a growth analyst decomposing a change in cost per acquisition. I will paste funnel metrics for the current and prior period. Produce:

A) THE DECOMPOSITION: how much of the CPA change came from traffic cost, how much from click-through, how much from landing page conversion rate, and how much from downstream qualification — each as a share of the total change, with the arithmetic shown from my numbers only.
B) THE VERDICT sentence: the single largest contributor, and whether the others are noise against the variation range I provided. If I gave no range, write "variation range needed" and say how to compute it from my data.
C) THE ORDERED FIX LIST: what to change first given the decomposition, each with the expected direction of effect and how long before the result is readable — plus what to explicitly NOT touch while the first fix is in flight, and why.

My data: [PASTE: by period — spend, impressions, clicks, CPM, CPC, sessions, landing page conversions, leads or sales, qualification and close rates, plus any known changes to ads, pages, or audiences]

Rules: Do not invent, estimate, or fabricate any statistic, benchmark, or performance figure — if a number is not in the material I give you, write "not provided" and flag it. Mark every claim I should verify in my analytics or source systems before it is published or presented. Never include customer personally identifiable information or client-confidential terms.

What changed for Marketing

How to run “CPA is up: split the ad problem from the page problem”, step by step

The situation this prompt is built for: Cost per acquisition is climbing and two teams are blaming each other. Decompose the funnel arithmetic and settle it with the data instead of seniority. Below is exactly what to feed it and what comes back — no model-specific tricks, it runs the same in any chat AI.

Why this structure works

The ad-versus-page argument is a decomposition question that almost nobody actually decomposes, so it gets settled by whoever outranks the other. Attributing the CPA move to its arithmetic components ends the debate in a single pass, and forbidding parallel changes while the first fix is in flight preserves the ability to read the result at all.

On Pro, pro personalization loads your funnel's normal variation ranges so "the biggest contributor" is judged against your history instead of eyeballed.

When to use it — and when not to

Reach for it when

• Cost per acquisition is climbing and two teams are blaming each other. Decompose the funnel arithmetic and settle it with the data instead of seniority.
• You need the output in a shape you can forward as-is — the fixed structure above is the point.

Skip it when

• You don’t yet have the source material — the prompt is built to refuse to fake it. Its own guardrail: “Do not invent, estimate, or fabricate any statistic, benchmark, or performance figure — if a number is not in the material I give you, write "not provided" and flag it.” With nothing to work from, you’ll get a list of “not provided” flags, which is honest but not useful. Collect the inputs first.
• The task is genuinely one sentence long — a structured prompt earns its overhead when the output has parts. For quick one-off questions, just ask.

Adapting today’s prompt for adjacent roles

“CPA is up: split the ad problem from the page problem” sits in the Paid Media & Attribution lane of the marketing pool. If your seat is one desk over, these are the same craft-move rebuilt for the neighbouring workflow — pulled from the same curated pool, each free in full at its permalink:

You are a competitive strategist running a campaign teardown. I will paste what is publicly observable about a competitor's campaign. Produce: A) A TEARDOWN TABLE:…

You are an email copywriter running a subject line lab. I will describe the email and audience. Produce: A) TWELVE SUBJECT LINES in a table, grouped by psychological…

You are an email deliverability and engagement analyst. I will paste my program metrics over time. Produce: A) A HEALTH READ per metric with its measurement caveat…

Common failure modes (and the fixes)

• Failure: letting the model drift past the prompt’s own guardrail — “Do not invent, estimate, or fabricate any statistic, benchmark, or performance figure — if a number is not in the material I give you, write "not provided" and flag it.” Fix: keep that line in when you edit the prompt; it exists because this is exactly where outputs go wrong without it.
• Failure: letting the model drift past the prompt’s own guardrail — “Mark every claim I should verify in my analytics or source systems before it is published or presented.” Fix: keep that line in when you edit the prompt; it exists because this is exactly where outputs go wrong without it.
• Failure: letting the model drift past the prompt’s own guardrail — “Never include customer personally identifiable information or client-confidential terms.” Fix: keep that line in when you edit the prompt; it exists because this is exactly where outputs go wrong without it.
• Failure: accepting the first pass. Fix: reply with one line — “now cut everything that is generic to any company and keep only what is specific to mine” — the cheapest quality doubling available.

Where AI is landing for brand and growth marketers right now

Context for today’s prompt, from the same screened sources the daily brief reads. Our read, with sources linked — the pattern across items like these is consistent: the professionals getting leverage from AI are the ones feeding it real working context, which is exactly the muscle today’s prompt trains.

• The Fed Finally Gets It (rss) — Tariffs, Hormuz, and fiscal policy are not good reasons to hike. The underlying growth trend and the asymmetric sensitivity of private sector spending to the level of interest…
• [Odd Lots] Hollywood Was Cooked Before AI, and Now It's Only Getting Worse (podcast) — Is Hollywood just screwed? Writers are earning less. There are fewer shoots taking place in Los Angeles. And people are freaked out about AI. But according to Hayes Davenport,…

Quick answers

Is “CPA is up: split the ad problem from the page problem” free to use?

Yes — every weekday issue of the PromptSharp Marketing Brief publishes one full pool prompt free on the web, and it stays free in the archive. Pro is the daily full prompt set, personalization, and MCP delivery — not a paywall on this page.

Which AI model does this prompt work with?

Any of them. Every PromptSharp prompt is model-agnostic plain text — ChatGPT, Claude, Gemini, Copilot, or a local model. No plugins, no custom GPTs; paste and run.

How is the marketing prompt of the day chosen?

Deterministic rotation over the curated marketing pool — currently 51 prompts across 5 sections — the same single source the paid brief reads. Same date, same prompt: the archive never silently changes under you.

How do I get this in my inbox instead?

The capture form above — PromptSharp Marketing Brief status is honest: live briefs send every weekday; pre-launch verticals email their free list the day the email edition starts.

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