I've been trying to make sense of our declining traffic and sales levels, so I turned to Google Trends to see if it could shed some light one what people are looking for...what I find is that the majority of search phrases trend downward. My assumption is the the overall total of search phrases in the Google Trends database keep growing, so volume of that term is being compared to all terms, making the trends display misleading, unless you tilt your monitor 7.356 degrees to the left. JK - any new ideas on this? or just more black box speculation?
I'd say you're right, Google Trends is useful for relative trends but not for absolute values year to year. That nearly universal downward tilt has been there since the service launched. It must be some artifact of the way the numbers get crunched.
Some of our previous discussions here show the same concern - for example [webmasterworld.com...]