One reason why online shoppers abandon shopping carts is the shipping fee, according to a recent survey by comScore Inc., conducted by PayPal. The study found that many consumers only proceed to checkout because they want to gather information not previously provided, for instance about shipping costs, delivery date and total order price.

Nearly half of online consumers who had abandoned a purchase in the previous two weeks said such information gathering was the reason they clicked on the checkout button. Just under a third said they intended to complete the purchase, but changed their mind.

The primary reason for not completing the purchase was cost, cited by 46 percent. Of those who abandoned the shopping cart, 19 percent specifically referred to shipping costs; 13 percent said they changed their mind or ran out of time, and 16 percent said they were comparison shopping.

Asked to identify from a list the very important reasons for abandoning a purchase, 43 percent said the shipping charges were more than they wanted to pay, and 36 percent said the total cost of purchase was more than they expected. Other reasons cited as very important were as follows.

More than a quarter said they wanted to look at other websites before purchasing. Nearly as many, 22 percent said they wanted to look at offline stores, and just as many said their preferred payment option was not available. One in five said the item was no longer available by the time they checked out. Just as many, said the wallet or payment option was not readily accessible, and 16 percent also said they were unable to contact customer service for more information.

While most respondents could not identify any change that would have led them to complete the purchase, 10 percent of those who abandoned purchased at larger merchants, and 20 percent who had left smaller retail sites pointed to lower shipping costs or free shipping. More than eight percent said a price discount would have led them to complete the purchase.

More than a third of those who abandoned their purchase ultimately returned to buy from the same online retailer. That included 36 percent who abandoned carts at large retail sites and 37 percent who did so at smaller merchant's websites. PayPal says its data shows that two thirds of online shopping carts are abandoned before purchase. That abandonment rate was put at 50 percent in a survey of online retailers last year by research and consulting firm, Forrester Research, and online merchant trade association, Shop.org.