when people say link unit have low ctr then why some people suggest to use link unit coz it can imporve ur earnings as well as ctr ? who is right?
Nobody - it's down to the individual's personal experience. If you have a link unit, with relevant links at the top of the page with your navigation tabs it's likely you'll get some click thrus. If on the otherhand your link unit is hidden away from the rest of the page content, you're unlikely to have much success. It would be honest to say that if you include a link unit you're not going to be any worse off than if you didn't have one.
Actually, I didn't place ad link units because it made my site too "cluttered" therefore I would recieve fewer clicks. It all depends on your layout design though..
Keep in mind that link units require the user to click twice before you get paid. I avoid them just for that reason alone.
Thats the reason some people avoid it but on other hand some people prefer it because the ads returned from link unit clicks are more targeted, hence more chances of clicks.
i always use one link unit, 3 adsense blocks and one or two search boxes. I know that I read not to do it, but I do it because the advisers are not the ones who give the money.