He said one unnamed charity client had missed out on significant donations because it had failed to improve the direct debit conversion rate by testing different versions of its donation form.
He added that websites were the perfect medium to test the success of direct debit forms because different ones could be tried. "It is easy to configure a site so that every third visitor to a donation page is presented with a different version," said Potts.
In one month, the charity recorded 3,674 visits to its direct debit page, but only 207 people - 5.6 per cent - followed through with donations.
A total of 2,537 people exited immediately and a further 56 completed the form but failed to make a gift.