For example, users may fill in part of a form, then click ‘back’, not realising they may lose the data they have just typed.
Since use of the ‘back’ button is ubiquitous, should this be a concern for forms designers?
Why do people use the ‘back’ button?
To answer this question, I ask myself why the users are using ‘Back’.
Maybe they want to lose the data. For example, a user may complete parts of a form, but then be confronted by a question they prefer not to answer (at least not in the context of their current relationship with the organisation or website). In such a case, use of the ‘back’ button does not result in accidental loss of data (although if many users were abandoning your form at this point, you might want to re-consider the questions you are asking or the point in the form at which they occur).
Another reason for hitting ‘Back’ is see-sawing, where the user goes back to review previous entries or information in order to tackle questions on the current page, then goes forward again to return to this page. See-sawing implies that you have failed to achieve ‘unity of topic’. Each page should be self-contained and self-sufficient, so that the user does not need to go back to find previous information.
A third reason is that the user thinks they are finished entering the data and hits ‘back’ to navigate elswhere. For example, many users will return to the Home page on a site to navigate from there to another point. You can also see this behaviour when people use search engines.
If this is happening, then you have failed to show users that they have not finished the task. This could be an appearance problem (lack of an obvious ‘submit’ button) or a conversational problem (users consider that the relevant questions have been dealt with). If you are experiencing this problem, further investigation is required to find out what users are thinking when they hit ‘back’. Refer also to the paper Designing usable forms: the three-layer model of the form .
Note that all these problems arise from poor User Interface design.
A final reason could be that the user has decided to do something else, and leaves your form with the intention of returning later, not realising that the data enterered will be lost. Offering a ‘save’ function may be a way to get around this issue.
Overall, my recommendation is to design the form so that the user completes it page by page without feeling the urge to abandon a page part-way through.
If each page is on a sensible topic, then users are likely to prefer to finish the page prior to moving elsewhere on the site.