CPA vs ROI Optimization…What’s The Best Practice?

March 12, 2010

Whenever I’m asked to audit a PPC account, my first question to the client is: how do you measure performance? It’s a simple question and the usual response is CPA (cost per acquisition) or ROI (return on investment). If the answer is CPA, then there are some follow-up questions: how many products or services are offered? And if more than one, then do they cost the same, or are they worth the same to the advertiser? What I’m getting at is that CPA is usually is a limitation of tracking – the advertiser cannot associate true revenue with the conversion. Managing to an ROI, and moreover, managing to maximize profit margin for each keyword will open up new doors for PPC efficiency.
Clients that manage to CPA generally have several products or services. To see the underlying issue with CPA optimization, consider the situation where we have two possible conversions: one worth $20 and one worth $40. If we optimize to an avg CPA of $30, we may be only selling $20 products and losing money. With ROI optimization, this is not a possibility. If CPA optimization is the only possible route, then there are a few best practices to find a good CPA to set as a goal. If the transactions occur online, then calculate the average order value and subtract the avg variable cost to the advertiser – this is the max CPA. If the online conversion is a lead which requires offline sales, then multiply this CPA by the average offline conversion rate to define the eCPA (effective CPA). Read the rest of this entry »