Warning: The number of queries per day per IP address is limited quite drastically by Google. Once you reach it, Google will not return any result.
Background information is available from Forbes, and from the original papers accessible from here and here.
How is the data scaled?
The data is scaled based on the average search traffic of the term you’ve entered.
There are two modes of scaling – relative and fixed – and the only difference between them is the time frame that’s used to calculate the average. However, fixed scaling is only available as a .csv export. Please note that the ability to see numbers on the graph and to export this data with either mode of scaling are available only after you’ve signed into your Google Account for Trends.
1.In relative mode, the data is scaled to the average search traffic for your term (represented as 1.0) during the time period you’ve selected. For example, if you entered the term dogs, the graph you’d see would be scaled to the average of all search traffic for dogs from January 2004 to present. But if you chose a specific time frame – say 2006 – the data would then appear relative to the average of all search traffic for dogs in 2006. Then, let’s suppose that you notice a spike in the graph to 3.5; this spike means that traffic is 3.5 times the average for 2006.
2.In fixed mode, the data is scaled to the average traffic for your term during a fixed point in time (usually January 2004). In our example, 1.0 would be the average traffic of dogs in January 2004. If you chose 2006 as your time frame, you would be comparing data for dogs in 2006 to its data in January 2004. Since the scale basis (1.0) doesn’t change with time, you can look at different time periods, and relate them to each other. (Note: For keywords without a historical record, it may not be possible to establish a fixed scale).
Do the numbers on the graph reflect actual search traffic numbers?
No. The numbers you see on the y-axis of the Search Volume Index (which you can see after you’ve signed in to your Google Account) aren’t absolute search traffic numbers. Instead, Trends scales the first term you’ve entered so that its average search traffic in the chosen time period is 1.0; subsequent terms are then scaled relative to the first term. Note that all numbers are relative to total traffic.
I see a number next to my search term at the top of the graph. What does this mean?
The number you see next to your search term corresponds to its total average traffic in the time frame you’ve chosen.
When comparing multiple search terms on a relative scale, the first term you enter will always be 1.0, as subsequent terms are ranked and scaled against this term. For example, you may see: blogs (1.0) and newspapers (0.51). In this case, newspapers has approximately half the searches of blogs.
If you export the data to a .csv file and you’ve selected fixed scaling, 1.0 corresponds to the average traffic for the search term in fixed point of time (usually January 2004), and all numbers are relative to this point. If you chose a time frame of 2007, the number you see for blogs (for example, 5.82) would mean that blogs has had approximately 5.8 times more relative traffic in 2007 than it had in January 2004. Similarly, the the number you see for newspapers (2.05) means that newspapers has about 2 times more traffic in 2007 than blogs had in 2004.
Note that the ratio between these numbers always remains constant and corresponds to how the keywords compare to each other; only the scaling basis (or the meaning of 1.0) changes.
Source: Google Trends FAQ
1.Explore Trends @ Google Trends
Copyright © 2013-2017 Jiri Pik
Document Version: Sunday, May 7, 2017