The form with one question

A charity's online donation page asked for name, address, telephone number, date of birth and how the donor had heard about them, before the payment details. Fewer than one in five people who started it finished.

The team removed everything that was not needed to take a payment. Two fields remained. Completion rose above half.

Every field on a form has a cost, and the cost is not the three seconds it takes to fill in. It is the moment of deciding whether to continue. A person who has already typed a name and then meets a request for a date of birth asks, briefly, why this is needed, and some proportion of people answer by closing the page. The question is reasonable and the form has no way to answer it.

The fields were there for sensible reasons. Someone wanted to analyse which campaigns worked. Someone else wanted to send thank-you letters. Each request was justified on its own and nobody was responsible for the total, which is the usual way forms become long.

The discipline that prevents this is a single rule applied without exception: a field may be added only if someone can say what decision will be made differently because of the answer. Most requested fields fail that test immediately, and the ones that pass are usually the ones nobody questioned.