Building a 'Sources of Truth' Doc So Your Marketing Numbers Stop Contradicting Each Other

20 September 2026·5 min read

Quick answer: A sources-of-truth doc is one simple page that states, for each key marketing number, exactly where it comes from, what counts as that number, and who owns checking it — so when your ad platform says one thing and your bank account says another, everyone knows which figure to trust. It usually takes about an hour to build and saves hours of confused, circular meetings later. 📈

If you’ve ever sat in a meeting where the ads dashboard says 40 leads, the CRM says 25, and whoever answers the phones swears it was "a slow month," you already know the real problem: nobody agreed which number is correct before the meeting started. Different platforms count different things — a "lead" in an ad platform is often just a form submission, while a "lead" in your CRM might mean a genuinely qualified enquiry. Small businesses don’t need more dashboards 💡, they need one page that settles the argument before it starts.

What most businesses get wrong

Most businesses treat every dashboard as equally correct, which means whoever’s citing the most flattering number in the room tends to win the discussion, regardless of whether it’s the most accurate one. New tools get bolted on — a booking system here, a call-tracking number there — without ever updating what actually counts as "the" lead number. And platform-reported numbers, which are often generously counted, get treated as gospel instead of being checked against what actually lands in the bank account.

No single number is agreed as the "official" one for each metric
Nobody owns keeping definitions current as tools change
Ad platform numbers are trusted over CRM or bank records, when it should often be the reverse
Reports get built from memory in the meeting itself, rather than from an agreed reference

The One-Page Sources of Truth Doc

Build a simple table — a spreadsheet or shared doc — with one row per metric that actually matters to your business. For each one, capture:

Metric name — e.g. "Leads," "Website Visitors," "Revenue"
Source system — the one specific tool that’s the official record for this number
Definition — exactly what counts (e.g. "a lead = a submitted enquiry form OR a phone call over 60 seconds")
Owner — the one person who checks and reports this number
Check frequency — weekly or monthly
Known quirks — e.g. "the ad platform over-reports by roughly 20% versus what actually lands in the CRM — always defer to the CRM count"

Worked example row: Metric: Leads — Source: CRM, not the ad platform — Definition: a submitted contact form or an inbound call logged by staff — Owner: office manager — Frequency: weekly — Quirk: the ad platform reports roughly 30% more leads than actually appear in the CRM, so the CRM number always wins.

An ecommerce store selling across several platforms: Shopify, the ad platform and Google Analytics were all reporting different revenue figures for the same week. Building the sources doc meant agreeing Shopify order data was the single source of truth for revenue, with ad platforms only trusted for cost and cost-per-result. It stopped the weekly arguments — though refunds and discount codes still occasionally need manual reconciliation, so it’s not entirely hands-off.

A service business juggling a Google Business Profile, a CRM and phone tracking: phone enquiries weren’t automatically landing in the CRM, which made lead volume look like it had dropped when it hadn’t — it was just a tracking gap. Fixing it required paying for basic call-tracking software, a small ongoing cost that was worth it once the doc made the gap visible.

A business with multiple locations run by different managers: each location had quietly been counting “leads” differently for years, making any head-office comparison meaningless. Standardising definitions across all locations via a shared sources doc made comparison possible for the first time — though it took a full quarter of pushback before every manager actually used the same definitions consistently.

How to actually do this

List every number you currently glance at across all your platforms and reports.
Sit down with three months of your bank statement or actual sales records and check which platform’s numbers most closely track reality.
Assign one owner per metric — the person who checks and reports it, not a committee.
Note any known quirks or discrepancies between platforms directly in the doc.
Put the doc somewhere everyone actually looks — pinned in a shared drive or linked from your reporting template.
Review it at the same recurring team meeting so it never quietly goes stale.

💡 The goal isn’t perfect data, it’s an agreed reference point. You will never get every platform to match exactly — attribution windows, cookie rules and counting methods differ by design. The win is having one page everyone agrees to defer to, so meetings stop being about whose number is right and start being about what to do next.

Mistakes to avoid

Trying to make every platform match perfectly — chasing that wastes hours for no real benefit
Leaving the doc without a clear owner, so it goes stale the moment a tool changes
Building it once and never revisiting it as new platforms get added
Assuming a platform’s own reported number is automatically correct without checking it against real bank or CRM data
Making it overly complex with thirty metrics instead of the handful that actually drive decisions

Frequently asked questions

How many metrics should be on this doc?

Start with five to eight — leads, revenue, website visitors, cost per lead, and whatever else you actually make decisions on. More than that and it becomes another thing nobody reads.

What if two platforms will just never agree exactly?

That’s normal, not a failure — different tools use different attribution windows and counting rules by design. The point of this doc isn’t to force perfect reconciliation, it’s to document which number you’ve agreed to trust despite the gap.

Who should own this doc in a small business?

Whoever already looks at the numbers most regularly — often the owner, office manager or whoever runs your weekly huddle. It works best as one person’s clear responsibility, not a shared task.

Do we need special software to build this?

No — a shared spreadsheet or doc is genuinely enough. The value is in the agreement and the habit of checking it, not the tool it lives in.

Keep reading 🤍

Written by

Kate, founder of Chronically Online

I help Gold Coast and Brisbane businesses grow with branding, websites and marketing that actually works.

Work with me ✦