This is not a new story, but it’s still a good one. User Interface Engineering has a good article about how a small change to the checkout process resulted in big increases in the number of successful checkouts for an online retailer (hmmm, Amazon perhaps?)
It’s a good example of how users will give up when presented with obstacles and barriers at a vulnerable moment.
Although this article is a few years old, and I think that most decent e-commerce sites have learnt these lessons (Whitcoulls for instance does not require an account to make an order), it’s still a pertinent lesson for anyone designing an e-commerce site.
I suppose the challenge is to design the checkout system to have as few fields and steps as possible, and then to carefully add the extra options in such a way that does not prevent or slow anyone down from achieving their goal.