How to deal with position bias in search?
What are your output (prediction) and inputs?

The bias in itself is very important in predicting the click-through rate, but definitely less useful if you want to assess your ad copy/ page title in relation to the click-through rate.

One potential way to do that is to model the impact of the position of the ad / (or page, if it's for SEO), and try to normalize the data either by including the impact factor in your model or adjusting the result by the impact factor.

I would suspect it would be a log function, as the number of clicks tend to drop significantly after the top 1/2 of the first page.