Whether you're talking about natural or paid search, the quality of your traffic is key to ROI. Not all traffic sources are created equal. On the one extreme, visitors may browse a site, leave, and never come back; meanwhile, some visitors may frequent the site, convert, and refer more traffic to you. Most visitors will be somewhere between the two extremes.

SiteLogic recently posted an article about traffic from social networks or media sites. Essentially, not all traffic is created equal. Social media traffic tends to drive "a lot of traffic, very fast. However the vast majority of that traffic is not engaged ...".

At some point, sites may start to discriminate among traffic sources to ensure quality versus quantity. In paid search, the CPA ad model would enable you to do that; the CPC/CPM model wouldn't work so well. In natural search, discrimination of traffic sources rarely comes up as a issue - afterall, it's free traffic.

Read the full posting on SiteLogic here.