Google Trends is one of the tools we use to study trends. We've found that search term volume is very useful for trend spotting and tracking. We've also found search term volume is a good leading indicator of changes in trend popularity.
Below is the Google Trends list of cities ranked by the use of the search term "coworking." Google develops this data by calculating the ratio of searches for the search term coming from each city divided by total Google searches coming from the same city. It displays the 10 cities with the highest ratio.
We think of this data as an "intensity indicator," in this case showing us the cities where coworking is generating the greatest interest.
While we often refer to Google Trends, we try not to read too much into the data. Google itself warns users that the data may or may not be real accurate. Great quote from their Google Trends FAQ: "We hope you find this service interesting and entertaining, but you probably wouldn’t want to write your Ph.D. dissertation based on the information provided by Trends."
But our work indicates this data is directionally correct and very useful.