What is a good way to keep pulse on overall search volume and how you are doing relative to your competition?
There are several tools out there, SEMRush and SpyFu being two I use, that help you do so. However, where they get their data is kind of opaque, and unless I see a patern in the data from BOTH of them, I generally don't worry about it. Google provides impression share for most cases within AdWords. This provides a lot more context than you might realize. You got 1000 impressions, and have a 90% impression share? Then by simple arithmetic, you know there were only 1111 (or so) queries in that time period that would have matched your keywords and match types. If you're looking at text ads, then you have the added benefit of Average Position to further identify where your competitors are pushing you out. Search volume is then a function of match type and catalog breadth. If you watch your impression counts and shares over time, you can even trend the audience size.
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