A while back, I overhauled my shopping cart system so that it guided the user through the process better. I'll admit that I didn't bother tracking the difference that it made, but my general impression was that the change was for the better. Today, I realized that I could streamline the checkout process further, and this time, I'm prepared to come up with at least some statistics to prove whether it results in less abandoned carts.
What I realized today was that there was really no reason for my system to ask for names, email address, or addresses except when the order was going to be paid for by check or money order. In those cases, the user prints out a page to mail in with their payment, and I'd like that page to have everything on it--what they ordered and where to send it. But when they pay by PayPal or credit card, the payment processing system asks collects their name and email address, and when they order physical goods, asks for a shipping address too.
I was capturing that data before partly because I needed to with my old credit card processor, and partly for my own convenience. But the way I process credit cards now, I don't need to do it, and it's really not about my convenience, it's about the customer's convenience and level of comfort. How much can I ask of a potential customer before they decide they're not sure they can trust me? Sure, they'll have to give the information up later in the process, but that will be on a site they're more likely to already trust, and it will be after they've invested a little more in the process and have already made more of a commitment to follow through to the end.
Another upside to today's change is that it enabled me to rearrange the shopping cart screen a little in a way that puts the link to the next step in the process after they add something to their cart (select a payment method) at the top of the screen rather than off to the side where they might have a harder time finding it. (I had hilighted the next step pretty clearly before, but there's always somebody who just can't figure it out and writes you to say that your checkout process is too hard.)
After I have a chance to see whether this change has more of an effect that my change of one of my sales pages to a "sales letter" (which has had no discernable effect), I'll add a comment to this entry letting you know how much difference it made.