Google Changes Click & Impression Calculations in Search Console
Google has changed how it calculates clicks and impressions in the Search Analytics report withim Search Console.
No formal/official announcement has been made regarding the change (so no actual details were provided about the degree of this change) but SEO's and webmasters should definitely take a close look to determine if data associated with their sites has been affected.
Google’s John Mueller provided some additional, rather useful, insight about the change on Google+, explaining that other changes include how Google counts links shown in the Knowledge Panel, in various Rich Snippets, and in the local results in Search (which are now all counted as URL impressions).
"One question that has come up a few times regarding Search Analytics is how local results are handled. Luckily, it’s pretty straightforward: if a URL from your site is included in the local result, it’s counted as an impression. If the same URL is included multiple times (e.g., multiple franchises in the same area with a shared web URL), that URL is just counted once. If a local result (w/web link) + a natural web result are included in the same results page, then that’s counted as 1 site impression (which is used for the view by query, for example), and the URLs individually get the page impressions (which is used in the per-page view)."
Most SEO's and webmaster likely won't notice much a change in their Search Analytics report, but Google did indicate that mobile apps might show the largest shift.