Hello, I am an advertiser on Google around 2 years now and recently I have started on Yahoo. As you may know, Google is twice expensive than Yahoo in pay per click (an estimate) Most of the time I get 100 clicks from Google and 40-50 from Yahoo (less budget for yahoo). The thing is how can I know that which search engine gives more ROI? Is there a way or do I need to ask to the customers always from which searc engine did you find us? I hope it is clear. Thanks.
It's not the search engine or the PPC that gives you ROI, it's what happens after they click through to your ad. Is your landing page effective at making conversions? That's the real question.
"Is there a way or do I need to ask to the customers always from which searc engine did you find us?"...that would certainly be a good start. It would also be useful to know how much each customer gives in ROI... i.e. most of your visitors may come from Yahoo, but its the Googler's that have a better conversion rate. You want want to look into google analitics, as the 'big' conversion trackers (dart, atlas) are far too expensive for a small business. Going back to the first point about putting the question "where did you find us", I'd suggest putting that on the conversion page that you are most bothered about, i.e. order page.
Conversion tracking. Add a conversion tracking pixel from each engine, or send people to pages that will call a different shopping cart path (or some variable that will indicate to you which engine they came from) for your campaigns on each engine.
Track the conversions on your site through Google Conversion Tracking codes which should be placed on the confirmation pages. Use analytics code for better analysis.