This session was held by David S. Platt whom wrote a book with the same title.
It was a fun session. David explained that developers cannot design software with the assumption that if the developer thinks it is good software then it is good software. Instead you should design software so that the customer thinks it is good software.
Most developers are forexample male with high education, however customers are often “uneducated” and has a population of 52% female based on the numbers presented by David. Just this difference can be used to point ut the differences between the users and the developers.
David raised a great analogy when it comes to user interfaces. Assume that 1 click in an interface takes roughly 1 second. This 1 second can the be directly translated to cost in financial terms.
Consider then that this 1 second is done on 1000 PCs over the world, then the cost is multiplied by 1000, if its done 35 times an hour on 1000 PCs over the world the cost for such a design would be 1 * 35000 * AVG.PricePerSecond /hour.
This gives an execellent measurment to analyse different UI desicions based on a number, and also a good way to have a discussion about UI with financially oriented people.