The useful question is not whether rankings improved. It is whether the firm's SEO investment is producing attributable matters and economic value at a cost the partnership accepts. That requires a repeatable measurement policy rather than a collection of favorable marketing metrics.
For each evaluation period, define what counts as an SEO-sourced matter, what revenue measure will be used, and which costs belong in the denominator. Keep those definitions stable enough that one reporting period can be compared with the next. If the firm changes attribution rules whenever the result looks inconvenient, the ROI number stops being decision-useful.
The core inputs are practical: the origination source recorded for signed matters, collected or consistently estimated matter value, and the complete cost of the search program. Supporting visibility data can help explain movement, but it should not be substituted for client and revenue evidence.
Channel comparison also needs the same accounting rules. When the firm compares organic search with paid acquisition or another source, use equivalent definitions for signed matters, revenue, and acquisition cost. A 12-month view can provide more context than a 90-day snapshot, but neither period proves what will happen next.
This guide cannot guarantee compliance, and responsible legal, medical, or regulatory reviewers remain required before regulated claims, disclosures, client-facing statements, or marketing conclusions are published. It also cannot guarantee rankings, matter volume, revenue, or ROI. Treat the calculations as management evidence whose quality depends on the underlying records.