About two years ago to this day Google started manipulating the search results when you were logged into a Google Account (Google Analytics, Gmail, etc). Yes, manipulating. At that time your search results could be manipulated based on your own search queries and clicking behavior. If you were logged into your account, then you noticed the search results (a.k.a. keyword ranking) differences.
In 2008, the search engines introduced a way where people can re-order to their search results. Again, you needed an account and you could manually increase or decrease a search result based on your preferences.
Now we are finding the search results are being manipulated whether or not you were logged into a Google account. This type of ranking manipulation is due to personalization and is changing organic search once again.
Using an API the organic search results might show a ranking of 5 for a particular site. However, Google is re-ordering or "personalizing" the search results to show that site is ranking number 12 in my case.
While not wide spread as of yet - you may have noticed this in the upper right hand corner of a Google search result page. You can recognize this by the phrase "Customized based on recent search activity. More Details."
If you click on More Details will provide a brief explanation for their manipulation of the search results.
There are a multitude of factors impacting personalized search results including universal search (e.g. multiple content sources), behavior and user intent of the query.
If the search results are being manipulated - is personalization a good thing?
Absolutely – it provides you the ability of acquiring customers at different stages of the buying funnel.
Instead of only focusing efforts at late stage buyers where user intent is often key, now you can strategically align your website to appeal to early stage buyers that are often looking for basic information. In contrast mid stage buyers are often looking for comparison information.
Assuming you want to maximize your customer acquisition strategies, your search engine optimization strategies must change accordingly. Chances are your website will need new content to address the personalized needs of that prospect at those different buying funnel stages.
Markets have different buying funnel stages. Some consumer buying funnels are short, 3 stages and take minutes to hours. In contrast some B2B buying funnels are complex 6-8 stage environments and take 18 mos. The exact buying funnel process will depend upon your business.
Personalization also means that relying on tracking organic rankings as a primary SEO campaign metric is not a best practice. Keyword rankings are a just an indicator.
With personalization your primary SEO campaign metric should be return on investment (ROI). As such your SEO campaign should be judged on traffic metrics (e.g. keywords, leads, sales) and measured with campaign metrics (e.g. cost per lead, cost per sale). If your SEO campaign is not tracking these types of metrics, start now so you can begin to properly understand the ROI from your SEO campaign.