Beyond Vanity Metrics
Every media buyer has sat in a client meeting where someone asks, "But how many impressions did we get?" While impressions have their place, they're often a distraction from the metrics that actually drive business outcomes.
In this guide, we'll break down the KPIs that matter most — and explain how to track them effectively.
The Metrics Hierarchy
Think of advertising metrics as a pyramid. At the base are activity metrics (impressions, clicks), in the middle are efficiency metrics (CPC, CTR, CPM), and at the top are outcome metrics (ROAS, CPA, LTV).
Tier 1: Outcome Metrics (What Clients Care About)
Return on Ad Spend (ROAS)
ROAS is the gold standard for media buying performance. It answers the simplest question: for every dollar spent on ads, how much revenue came back?
ROAS = Revenue from Ads / Ad Spend
A ROAS of 4.0 means $4 in revenue for every $1 spent. But context matters — a 2.0 ROAS might be excellent for a high-margin SaaS product but terrible for a low-margin e-commerce brand.
Cost Per Acquisition (CPA)
CPA tells you how much it costs to acquire a customer. Unlike ROAS, it doesn't require revenue data, making it useful for lead generation campaigns.
CPA = Total Ad Spend / Number of Conversions
Customer Lifetime Value (LTV)
The most sophisticated agencies factor LTV into their media buying decisions. A $200 CPA looks expensive until you know the average customer is worth $2,000 over their lifetime.
Tier 2: Efficiency Metrics (How You Optimize)
Click-Through Rate (CTR)
CTR indicates how compelling your ad creative and targeting are. Low CTR usually means your message isn't resonating with the audience.
Cost Per Click (CPC)
CPC helps you understand the competitive landscape. Rising CPCs in an auction can signal increased competition or declining ad relevance.
Conversion Rate
The percentage of clicks that turn into conversions. This metric bridges the gap between ad performance and landing page effectiveness.
Tier 3: Activity Metrics (Directional Indicators)
Impressions and Reach
These tell you how many people saw your ad. They're important for brand awareness campaigns but shouldn't be the primary KPI for performance campaigns.
Frequency
How many times the average person sees your ad. Too low and your message doesn't stick. Too high and you risk ad fatigue.
Common ROAS Pitfalls
1. Attribution Window Games
A 28-day click attribution window will always show higher ROAS than a 7-day window. Make sure you're comparing apples to apples across platforms and time periods.
2. Ignoring Incrementality
Just because someone clicked an ad before purchasing doesn't mean the ad caused the purchase. True incrementality testing (holdout groups, geo-lift studies) reveals the real impact of your ads.
3. Platform-Reported vs. Actual
Every ad platform inflates its own numbers. Cross-reference platform-reported conversions with your analytics tool and CRM data.
Building a Metrics Dashboard
The best media buying dashboards combine data from multiple sources:
- Ad platforms — Spend, impressions, clicks, platform-reported conversions
- Web analytics — Site behavior, multi-touch attribution, conversion paths
- CRM/revenue data — Actual revenue, LTV, customer segments
- Financial data — Margins, overhead, true profitability
When all four layers are connected, you get a complete picture of campaign performance — not just what each platform wants you to see.
Key Takeaways
- Focus reporting on outcome metrics (ROAS, CPA, LTV) that map to business goals
- Use efficiency metrics (CTR, CPC, CVR) for day-to-day optimization
- Treat activity metrics (impressions, reach) as directional, not definitive
- Always cross-reference platform data with independent analytics
- Factor in attribution windows and incrementality before celebrating ROAS numbers
The agencies that master metrics don't just report numbers — they tell stories about what's working, what's not, and what to do next.