A conversion rate is a fraction: the visitors who did the thing, divided by the visitors who could have. The numerator has to be defined before anything can be optimised, and in Google Analytics 4 that definition is a key event, an event marked as measuring an action that matters to the business; any event collected can be marked as one, and a Google Ads conversion can be created from it. The denominator is whichever audience the question is about: all visitors, visitors from one campaign, visitors who reached the checkout. Optimising the wrong fraction, a sign-up rate counted over visitors who came for a job advert, produces precise figures without meaning.
The work has a fixed order. First measurement: where in the path visitors leave, read from the analytics funnel, session recordings and the form's own field-level drop-off. Then a hypothesis about why, from the evidence and from asking a handful of real users to complete the task while thinking aloud. Then a change, and a test of whether the change moved the number, which is what A/B testing is for. Google retired its own testing tool, Optimize, on 30 September 2023 and now points users to AB Tasty, Optimizely and VWO through analytics integrations; the method does not depend on the tool.
The usual findings
A required field nobody needs (phone number on a newsletter form). A price that appears only at the last step. A form that fails silently on a phone. A checkout that demands an account before it shows delivery costs. Each is found by watching, not by guessing, and each is fixed by removal.
| Stage | What to look at | Typical fix |
|---|---|---|
| Landing | Does the page answer the query that brought the visitor? | Match the headline to the ad or the search; show the price |
| Consideration | What question stops the visitor here? | Put the answer on the page: delivery, returns, who it is for |
| Form or checkout | Which field or step loses people? | Remove it, or move it after the commitment |
| Confirmation | Did the visitor know it worked? | A clear success state and what happens next |
The practice connects the channels. SEO and paid search bring the visit and are judged by it; conversion work decides what the visit was worth, and its result changes the arithmetic of both. A landing page that converts twice as well lets the paid account bid twice as much per click for the same cost per customer, which is why the conversion and web optimisation topic sits beside the analytics and attribution one and why the Google Analytics and Ads Measurement certifications both test the key-event setup the work rests on.