CRO works hand in hand with Web Analytics to ensure that the traffic that makes its way to your website, stays there and buys. Its as simple as that. CRO gives you conversions.
This is all about data. Who is coming to your website? Where are they coming from? What time of day do they visit and how long do they stay? What pages do they visit and most importantly, why do they leave without buying? If you have all of this information, you have the holy grail of website sales. You have an audience that wants to be there and wants to buy.