I found myself giving this advice to two people today.  It came in the context off preparing a presentation for upper management.  The desire was to communicate an understanding of what (and why) we are creating a piece of technology.  The difficulty was in trying to convey the information without overwhelming the audience.  This can be tricky.  Engineers are especially bad at this.  Why?

Engineers know a lot about what they are working on.  It's fair to say that they know more about what they work on than almost anyone else does.  Engineers are also taught to be accurate.  Being inaccurate gets you in trouble when you are designing something.  You can't be "close enough" in the weight-bearing characteristics of a bridge.  You can't be "close enough" to the specification when writing a class driver.  You have to be accurate.

Managers of engineers, on the other hand, know less.  It's not that we're dumber, it is that we are more diversified.  Consider the mind to be able to hold a finite capacity of knowledge.  It can either be filled with a lot of knowledge on a few topics or a little knowledge on a lot of topics.  Engineers are the former, managers the latter.

Therein lies the rub.  Engineers need to convey some subset of their knowledge to management.  However, management does not have the same understanding.  Management doesn't need it and probably can't afford it. 

When you ask an engineer to summarize, he or she will try to be very succinct but not lose any information.  This actually amplifies the problem.  Now you have the same amount of technical detail but with less explanation.  That's not a solution.

Instead, the solution must be lossy.  You have to throw away information in order to convey the main point.  Sometimes when you throw away that information, things get a little distorted.  That is to say, inaccurate.  This grates on most engineers.  However, it is exactly what is needed.

Let's use an example from another realm of life.  There is a story that George Washington cut down a cherry tree when he was young.  He was so honest that he went and told his father what he had done.  Is the story accurate?  We don't know.  Probably not fully.  That's okay though, we're trying to teach a moral about honesty and to describe the character of the United States' first president.  Those goals are both accomplished.  Trying to explain how it probably wasn't a cherry tree or it wasn't his fathers or how he took a month to tell or even how in other dealings in life he wasn't always honest may be accurate, but they distort the true picture.

Now let's look at the real world case.  We're trying to convey why we should test audio systems for their output level.  The engineer wants to say something like, "Full-Scale Output Level (or just Output Level for short) on a PC is the amplitude of the analog signal that comes out of the jack/speakers when a digital full-scale waveform is applied to the codec."  There's a great detailed description here.  Instead, to describe this quickly one might just say, "Output level is volume and if it isn't high enough, the volume won't be high enough."  That's not fully accurate, but it conveys the necessary information better.  If someone is really interested in the subject, there is plenty of time to go into detail. 

The important thing is to convey a kernel of truth in a way someone can easily latch onto.  Conveying something wholly false is bad, but so is conveying the truth in so much detail that it can't be grasped.  Often times it is necessary to trade accuracy for understanding.