Two different denominators
Cost per conversation uses conversations as its denominator. Qualified CPL uses only leads a person reviewed against an explicit qualification rule. Conversation count can add context, but it cannot replace qualified leads.
A hypothetical message example
Hypothetical example: USD 90 in spend produces 18 conversations and 3 manually qualified leads. Cost per conversation is USD 5, while qualified CPL is USD 30. The gap is evidence about qualification, not inferred revenue.
Write the qualification rule
Before reading the result, state the market, product fit, intent, and contact-quality checks used by the reviewer. Do not infer buyer quality, order value, or revenue from message volume.