A channel might deliver leads at £8 each and look like the winner. But if the client qualifies only one in ten, the true cost of a lead worth chasing is £80. Another channel at £20 CPL that qualifies half its leads costs just £40 per qualified lead — and is quietly the better buy.
cost per qualified lead = spend ÷ client-qualified leads
Signal computes this per channel automatically as the client qualifies leads, then reranks the channels and writes plain-language recommendations from it. That is the whole point of the platform: turn a shared spreadsheet argument into one agreed, honest number.