In The Pragmatic Programmer this term is introduced and "linearly independency" is used as an example for orthogonality.
How do you explain the same thing to a non-technical person and why independency is a good thing to have? Are there "real-life" (i.e. non-geek) examples for this concept?
For example, a car has orthogonal components and controls (e.g. accelerating the vehicle does not influence anything else but the components involved exclusively with the acceleration function). On the other hand, a non-orthogonal design might have its steering influence its braking (e.g. Electronic Stability Control), or its speed tweak its suspension.[1] Consequently, this usage is seen to be derived from the use of orthogonal in mathematics: One may project a vector onto a subspace by projecting it onto each member of a set of basis vectors separately and adding the projections if and only if the basis vectors are mutually orthogonal.
Wikipedia provides a great answer: http://en.wikipedia.org/wiki/Orthogonal
One of the simplest examples around everyone's house is the home theater.
TV, Amplifier/receiver/tuner, DVD/CD player, speakers, DVR, Cable/satellite/broadcast box, and any other toys (game cube).
They're all independent. Each can be upgraded or downgraded independently. And they have well-defined interfaces that makes interconnections possible. But the interfaces are relatively unique: video is not interchangeable with audio, but they do share a common physical interface.
There's plenty of real-life examples of orthogonality. In general, two things are orthogonal if changes in one have nothing to do with changes in another. Here are a few offbeat cases:
Just pick two completely unrelated metrics, and you've come up with two things that are orthogonal to each other.
Just replace "orthogonal" with "independent." They mean the same thing, and everyone understands the latter.
To "explain the benefits," you can simply point out that "messing with X doesn't affect Y." Most people can see why this is a good thing.
j_random_hacker is completely right when he says you should simply replace "orthogonal" with independent.
However, independence/orthogonality is not in itself a good thing. Thus I would not recommend to try to persuade non-technical people about any supposed benefits. There aren't any - without a specific context.
I thought this was a neat answer, which focuses on side effects: (Source)
"Your monitor has orthogonal controls. You can change the brightness independently of the contrast level, and (if the monitor has one) the color balance control will be independent of both. Imagine how much more difficult it would be to adjust a monitor on which the brightness knob affected the color balance: you'd have to compensate by tweaking the color balance every time after you changed the brightness. Worse, imagine if the contrast control also affected the color balance; then, you'd have to adjust both knobs simultaneously in exactly the right way to change either contrast or color balance alone while holding the other constant."
I would try to describe it by explaining where orthogonal comes from: each thing lives in its own dimension and can move in it without affecting anything from the other dimension.
No matter how much you move along the x axis, your y-value doesn't change; x and y coordinates reside in orthogonal dimensions. (the x-axis and the y-axis).
That's a good thing because, well, suppose x and y were not independent, this means that every time you change x, y will also change, but chances are, you only want to change x, not y, so now you have to go back and fix y, and btw when you do that x could change again on you!
I believe it is seldom possible to explain anything to such a person. For a person to identify as or be identified as "non-geek" means that one of the following cases applies:
Orthogonality can be succinctly explained as absence of crosstalk between control variables, but this is unlikely to mean anything to someone who thinks the pinnacle of technical sophistication is knowing how to connect an Xbox to a TV.
I'd use the example used in the book for a not orthogonal control: A helicopter.
If you want to fly faster you have to put the nose of the helicopter down. But you also have to increase throttle, to stay at the same altitude, which in turn will cause the helicopter to spin, which you have to prevent by yet another action.
This is not the direct answer but by reading articles at betterexplained you may get some good idea.
Perhaps you could explain it in terms of supply of goods or services. For example, gas and electricity.
You can treat gas an electricity as orthogonal, and this has strong advantages. Imagine you have a separate gas supplier and electricity supplier. If the gas supplier starts overcharging you can move to a different supplier, while staying with electricity supplier you're happy with.
Nowadays (in the UK at least) it's common for the same commercial entity to bundle gas and electricity into one account. You might save money by doing this. It might be more convenient to get one bill instead of two. But you sacrifice flexibility - you can't change your gas supplier without affecting your electricity deal. It would be a wrench to split things out so they are orthogonal again.
That's akin to the choices you make when developing software. There may be reasons for non-orthogonality. By not separating concerns you might gain performance, or simply hack something up faster. But you'd be sacrificing maintainability. Just as you can't change gas supplier without changing electricity supplier, you can't change your logging code without touching your billing code (for example).
Consider a refrigerator with a freezer, the usual sort of thing with two compartments and two doors. It will probably not have two independent cooling systems.
Now suppose you control how much cooling you get and how much goes to which compartment. That gives you complete control, right? Except that you can spend days getting it right, particularly if it's not well labeled. There's no clear way to make the freezer colder without affecting the refrigerator temperature. All you can do is turn up the cooling and the amount going to the freezer.
That's two functions not being orthogonal, or independent.
Now suppose that you have one knob for each compartment, and it's the refrigerator's job to figure it out. It will have thermometers in each compartment, and adjust appropriately. If you want to keep the ice cream harder without freezing the milk, you adjust the freezer control.
That's two functions being orthogonal.
It should be obvious which is easier to use.
Well, I've been Googling "Why orthogonality" and I find myself here in the middle of a strange land. I am "Bob the Builder" and I have taken a geometric stance in life of preaching to the inhabitants of this constrained world of orthogonality to change their ways and embrace rhombic dodecahedralism. Please join my quest if you have a will. It may well apply.
http://www.hexpressionism.com/2008/07/architectural-dodecahedronism.html