Marketing teams usually report impressions, clicks, click-through rate and cost per click. These are useful for running a campaign day to day, but they do not answer the question management asks: what did the organisation get back from the ad budget?

The answer is not to drop these metrics but to arrange them on a clear ladder. At the bottom sit media metrics; above them are key events such as an enquiry or a purchase; then the business outcome; and at the top, incrementality, meaning what would not have happened without the ad.

The practical rule: every metric in a management report should sit on one of the top two rungs, or explain movement in a figure that does.

ROAS and ROI: why they are not the same

Google Analytics defines return on ad spend (ROAS) as the total revenue earned for every unit spent on advertising, and cost per key event as total cost divided by the number of selected key events. ^[1] In other words, ROAS compares revenue with ad spend alone.

ROI asks a different question: how much profit is left after deducting the cost of what was sold and the cost of the ads? That is why campaigns with an apparently high ROAS can still be losing money.

Hypothetical worked example

An online shop spends AED 20,000 on a search campaign in a month, and reports attribute AED 80,000 of sales to it. ROAS is 4.

But the products’ gross margin is 30%, so the gross profit on those sales is AED 24,000. After deducting the ad spend, AED 4,000 remains, giving an ROI of 20%, not the 300% someone might read into the ROAS.

What matters most to management is break-even ROAS: 1 divided by the gross margin. At a 30% margin it is about 3.3. Any campaign below that figure loses money before any other costs are counted, however acceptable its number looks.

Start from the right event: an enquiry is not a sale

In GA4, actions that matter to the business are called key events, and they are the main source of conversions that can be shared with Google Ads. ^[2] For purchase revenue to appear in the total revenue metric, the purchase event must be sent with both value and currency parameters. ^[1]

The problem is that many Gulf service businesses do not sell on their website. The customer fills in a form or calls, and the deal closes by phone or in a branch days later. If you only count forms, you reward the campaign that generates the most enquiries, even if it is the weakest at closing.

This is where offline conversion imports in Google Ads come in. You store the Google Click ID (GCLID) with the lead’s details, and when the deal closes you send it back with the conversion type and time. An upgraded option, enhanced conversions for leads, adds customer-provided data such as email addresses, hashed, to improve matching. ^[4] Before uploading any customer data, check the requirements of the personal data protection law that applies in your country.

Who gets the credit? Attribution models in GA4

Attribution distributes credit for a key event across the ads and clicks that preceded it on the customer’s path. GA4 attribution reports offer three models: ^[2]

• Data-driven: uses the account’s data and machine learning to estimate each interaction’s contribution, and assigns fractional credit.
• Paid and organic last click: gives all the credit to the last channel the customer clicked through, ignoring direct visits.
• Google paid channels last click: gives all the credit to the last Google Ads channel, falling back to the previous model if there is no Google Ads click.

The first click, linear, time decay and position-based models were retired in November 2023. ^[3] The lookback window has two settings: a default of 30 days for acquisition events such as first visit, with 7 days as an option, and a default of 90 days for all other key events, with 30 or 60 days as options. Changing the model applies to historical and future data, whereas changing the window applies going forward only. ^[3]

The practical point: fix the model and window, state them in the report, and do not compare month with month after changing them without a note. And do not add up the conversions each platform claims, because each platform counts credit from its own angle, so the total can exceed actual sales.

Incrementality: would the customer have bought anyway?

Even the best attribution model describes what happened on the customer’s path. Guidelines published by IAB and IAB Europe in 2025 state that attribution and ROAS methods show what happened, not whether marketing caused the result. ^[6] Someone who searches for your brand name and then clicks its ad might well have reached you anyway.

Incrementality is the outcomes a campaign caused compared with what would have happened without it. The guidelines group measurement methods into four categories: experiments, model-based counterfactuals, econometric models such as marketing mix modelling, and hybrid proxies. Experiments are the strongest for proving causality, but they are costly and time-consuming. ^[6] The guidelines were written for commerce media, but their logic applies to digital advertising in general.

One example of an experiment is Conversion Lift in Google Ads, which splits the audience into a group that sees the ad and a control group that does not, and measures the difference in conversions. It reports metrics including incremental conversions, incremental cost per action and incremental ROAS, which is incremental conversion value divided by spend. The tool is not available to every account; you request it through your Google account representative. ^[5]

If the tool is not available, a simple geographic test gives an indication: pause the campaign in one city, keep it running in a comparable city for a fixed period, and compare sales, taking care that ads do not reach the control city through another platform. ^[6]

A monthly dashboard for management

Show each metric with its current value, target and three-month trend. Standardise the currency and how spend is counted, including or excluding tax, across reports so that marketing and finance figures do not diverge.

Checklist before the report goes up

1. Is revenue linked to closed deals, or only to forms and enquiries?
2. Are the attribution model and lookback window stated?
3. Was break-even ROAS calculated from a margin confirmed by finance?
4. Has double counting across platforms been removed?
5. Are brand-name campaigns separated from campaigns that bring in new customers?
6. Is there at least one incrementality test a year for the highest-spending channel?

Conclusion

Measuring ad return starts from profit, not the click. Calculate break-even ROAS, link campaigns to closed deals and fix your attribution settings, then test the incrementality of your largest spend lines before increasing their budgets.