Design Principle 2: If you can't justify it, remove it. Then ask questions.

At EmSense, one of our advisors, and a great mentor, has been Bud Tribble from Apple. The coffee sessions we have had with Bud in the Apple cafeteria have taught me some of the most important design principles. As we rolled out the EmSense in-home panel, our discussions focused on how to create the simplest and most intuitive interfaces for new users.

The second principle is one that is at the core of Apple: "If you can't justify why it has to be there, remove it immediately."

This may seem like a simple statement. The power is in rigorously using it in every design decision.

Can we cut this feature and still ship a great product? (Repeat for all features)
Do we have to have color, or will just the icon do?
Can we remove all borders from our UI design?
Is this text needed? Is it too verbose?

An Example. Turning a medical display in to a pocket watch.

One of the key areas where this was invaluable was in creating calibration systems for the EmBand (EmSense's Biometric measurement device). All the current systems when we started looked like a hospital display with detailed graphs, numbers and lots or real-time moving parts. This is where our design started, but we knew that no regular person could be successful with this.

Through much discussion and many software iterations (18 months), we realized that we could remove the technical graphs and replace them with a simple check box which says if each element of calibration is good or bad (Radio, sensors, placement,...).

Then, we realized that we could replace all the check boxes with a singe check box and a one line description of how to fix it.

Then, we tackled engagement, while the wiggling lines were intriguing for everyone, war realized that all that really needed to happen was for the person to sit still as the system did its work in the background. Therefore, we simplified the system again, while focusing on creating a single element which would engage them through the process.

Finally, the end product was a white screen with a black and white stop watch on it which counted down as the system calibrated and then a sentence describing the "fault" if there was a problem and what needed to be done to fix it.

By rigorously applying this second design principle (Delete first, ask questions later), we were able to take a system almost as complex as a fighter pilot cockpit and make it simple enough that we could ship in to homes and have equal success rates with regular people as with fully trained, professional administrators.