In 2011 Google essentially stripped off all of the search terms, resulting in a near +90% data disappearance, giving web analysts and the SEO crowd the term "not provided" blues. Left was the organic ranking "cd" parameter in order to do a SERP position check, but that has taken a hit in 2015.
Before the update over 45% of the Google referrals had the SERP position value present on computers (dataset = 10 weeks prior to update)
While not optimal at least it was one remaining source of data given the lack of search term data available in the referral string.
With that data a SERP position check could be done, essentially using the value to perform a bit of SERP analytics.
The Panda 4.2 update rolled out 17th July 2015 reduced one of the few remaining data sources provided with SERP clicks, instantly data on the SERP position dropped to record low levels of under 20%. How odd isn't it that a search company in reality hides data when provided search results?
After the Panda update (dataset 10 weeks after update) the most notable drop was seen on SERP clicks from computers, over 50% of the SERP position data vanished.
The same happened for mobile devices with a drop in SERP clicks, most likely a result of fewer searches done.
Oddly enough on tablets the occurrence of SERP position data increased while the clicks remained unchanged.
Unfortunately Google Webmaster Tools (GWT) provides reports on a per search term basis and URL basis, but without the glue to tie these together.
Given the visible drop (week 30) in data availability, the organic SERP position is reaching a near useless level given that the data is more of a sample than reliable volume.
Left for web analysts etc. is viewing the pages the Google search click lands on, well at least as long as that data is available.
Also available is GWT viewing of the impressions, clicks, and rankings of the search terms.
It seems Google is rendering itself irrelevant instead of doing the opposite.
By studying these long term effects on data quality every web analyst needs to take decisions when the data simply isn't reliable enough to be used moving forward. So if you are using any kind of Google SERP position tool or data it is time to do a check-up, else skewed reports will be delivered.