My hypothesis is A/B testing can move the needle for light engagement, like "try a free trial". But pulling out a credit card requires a lot of motivation, and the 0.1% of your visitors that have this motivation are relatively unaffected by your design.
That's not true in my experience. I've seen some big increases in the percentages that complete the checkout process through an iterative process of redesign/test for example.
The motivation behind a user purchase can be very different in different situations. If Mary is purchasing a new gearbox for the car, and she's already done a comparison shop, then she's likely to finish the purchase as long as it's vaguely sane. If Bob is impulse buying that new laptop bag he saw on swissmiss then every single grain of friction between Bob and the final "purchase" button is going to make it more likely that he remembers he really needs that $80 for groceries this week.
At some point you're going to reach a maximum of course and only see small or no increases - but, with my clients anyway, folk seem to be quite a long way from that in many instances :-)
That's not true in my experience. I've seen some big increases in the percentages that complete the checkout process through an iterative process of redesign/test for example.
The motivation behind a user purchase can be very different in different situations. If Mary is purchasing a new gearbox for the car, and she's already done a comparison shop, then she's likely to finish the purchase as long as it's vaguely sane. If Bob is impulse buying that new laptop bag he saw on swissmiss then every single grain of friction between Bob and the final "purchase" button is going to make it more likely that he remembers he really needs that $80 for groceries this week.
At some point you're going to reach a maximum of course and only see small or no increases - but, with my clients anyway, folk seem to be quite a long way from that in many instances :-)