If an adwords suggestion tool says a keyword is clicked on ( say ) 100 times a day... Is it possible to hazard any sort of guess about how many times it is actually search for? What percentage of surffers click on the ads?
The honest answer is it depends.
I think interest matters a great deal when trying to determine CTR. If people searching aren't interested in your ad, they won't click on it (obviously). The key to generating high CTR is generating interst and targeting your audience appropriately.
I personally buy AdWords for certain products and link to Amazon. I also target my keywords, which is an important step to increasing CTR.
Certain ads do better than others, of course, but I have an average of about 1.5% CTR for search ads and a .7% total (from lots of syndicated content listings).
Sometimes my ads go as high as 3% or as low as 1% (for search).
I'd be somewhat foolish to venture a guess for you, but depending on what you place, your ranking, and your targeting, you should expect a .5% ratio (the bare minimum) to a 3% ratio for most of your ads.
Hope that helps. :)
EDIT:
Almost forgot to mention: ALWAYS SET YOUR SPENDING LIMITS for your categories, otherwise you risk going bankrupt due to popular searches. While it might be tempting to overextend yourself, it's VERY risky. Caveat Advertisor. :)
I failed to heed my own advice, and I just got burned BADLY on a heavily-weighted item.
AGAIN: SET YOUR SPENDING LIMITS! Don't be overzealous like me and ramp up your ads at the risk of losing money. Take it slowly, gradually increase your well-performing ads, and be sure to prune out poorly performing ads/categories ever so often. :)
And be DOUBLY SURE to check that your ROI (Return On Investment) is consistent and fairly large.
