You must know that the CTR is very important because it indicates to you that at which point your copy made. If you have a well written advertisement, post, or the email which makes really the wire want to learn more, then you are sure to have the click raised by the rate. The commander of them is the souce from where your visitors come for example if they come from the search engines or some Web sites of reference. Visitors of Search Engine are considered more faithful and they review more number of pages and surely the possibilities of clicking on your advertisements increases. From my point of view it is the only factor which determines mainly your CTR.