Unfortunately shopping cart abandonment is the same as someone browsing in your store and choosing not to purchase. There are many possible reasons.Online shopping is no different.
According to a study done by the Baymard institute over 60% of all e-commerce visitors abandon their shopping cart.
People may even add items to their basket and return time and time again before actually ultimately making their purchase. These will be seen in your order manager as non completed/"passed for payment" order status - an abandoned cart.
For the below chart we look at data from Forrester Research's North American Technographics online survey, which shows factors involved in shopping cart abandonment.
For further information please see out previous article "Managing Shopping Cart Abandonment."