Google Correlate matches search trends based on drawn data series
As the diagram above shows, you use a pen tool to sketch out an interesting curve shape and then press the Correlate! button to initiate the search. Google then runs rapid correlation tests to discover the best fit patterns of web search activity to return a set of suggested search terms which match this shape. In the example below, the search term “centrino laptop” was the most closely correlated with the drawn shape.
It is essentially Google Trends – where you type in a query and get back a series of its frequency – but in reverse.