A clothing store can calculate a simple return ratio, but the interpretation becomes weak if the revenue window, attribution rule, page scope, and cost base do not match the way the SEO work was performed. A product-page rewrite, a collection restructuring project, and a paid social campaign can all influence different parts of the purchase journey, so they should not be judged as if every dollar of revenue has one observable cause.
Timing is the first source of distortion. Search work has an implementation stage, a crawl and indexation stage, and an observation stage before commercial attribution can be evaluated with any confidence. The source previously said competitive category pages can take four to eight months to surface. Keep that statement as historical planning context tied to the existing route, not as a ranking guarantee. A useful report names the stage being measured instead of treating an early revenue snapshot as the final ROI conclusion.
Attribution is the second source of distortion. A shopper may discover a clothing brand through a non-branded organic query, return through direct navigation, open an email, and later purchase after a paid retargeting interaction. Last-click reporting will credit the final recorded touch even though earlier channels contributed to the journey. That does not mean organic search caused the sale, and it does not mean the final channel alone caused it. The attribution model simply decides how recorded credit is distributed.
Seasonality is the third source of distortion. Fashion collections have changing demand and inventory. A page may perform strongly during the part of the year when its products are relevant and then contribute little after the assortment changes. Annual totals can flatten that pattern, while a very narrow campaign window can overstate it. Compare collections against the periods when inventory and demand were actually available, and keep later brand or direct purchases separate unless the attribution model records a defensible connection.
Decision rule: report SEO ROI at the collection or category level when that is where the work was concentrated, use an attribution model that the team can explain, include all material costs, and separate observed association from causal certainty. That produces a decision-ready view of whether to continue, expand, narrow, or stop a workstream without forcing organic search into a paid-campaign reporting model.