In Minimize Data Requirements, I talked a bit about allowing users to save incomplete data because there’s no reason to insist that all data must be provided before any of it is accepted.

While that may be a good negative reason (”there’s no reason not to”), there are also positive reasons for allowing this:

It makes your users’ lives easier.

Are you perfectly organized at all times? I know I’m not.

Requiring that saved data must be complete and valid (or at least valid-looking) at all times demands perfect organization from your users. It makes them collect all of the information you want up front and have it all available at the same time when they enter it. Removing that requirement means that they can enter as much as they know right now, then find the rest and come back later to finish.

It provides a record of user actions which were started, but not completed.

Suppose you have an online store for which users go through a series of three pages in the course of placing an order. Do you persistently store the partial data at each stage of the process or do you just keep it in the active session and write it all to the database at once when the final form is complete?

If you’re smart, you’ll make a permanent record of it at each stage. This information about what items a user started the purchase process for, but didn’t actually buy, can provide valuable insight into buying habits. If you’re using a recommendation engine (”people who bought X also liked Y”), then information about what users almost bought is almost as valuable as information about what they actually bought.

More importantly, though, this incomplete transaction data can highlight issues with your site’s effectiveness. If 90% of your users are starting a transaction, but abandoning it after the second step, then perhaps you should take a hard look at the third step (and, while you’re at it, make sure that the server is completing step two in a timely fashion) to determine why they’re not continuing at that point.

Incomplete or invalid data can show what mistakes your users are making.

Users will make mistakes and they will submit invalid data. That’s as inevitable as death and taxes.

Most software ignores invalid submissions, beyond throwing it back at the user along with an error message.

If yours saves it anyhow, though, then these invalid submissions give you a window into your users’ experience that will show you what mistakes they’re making. Once you know what mistakes are being made, you can attempt to determine the cause of the mistakes and make it easier for the users to get it right the first time instead of just scolding them for doing it wrong.

Like the data I’ve been talking about, I’m sure that this post is also incomplete. What other benefits or drawbacks are there to saving partial or incorrect data instead of rejecting it?