Here’s something I saw the other day:
SD = V(w + 2) / 3.6
where:
- SD = sight distance
- V = vehicle speed in km/h
- w = road width in metres
Note: The above formula is based on a walking speed of 1.0 m/s and provides a safety margin of 2 s. It is recommended that, at roads where there is likely to be significant use by people with ambulant disabilities, the walking speed be reduced to 0.8 m/s.
Do you see the problem?
Let me spell it out for you.
The equation is:
SD = V(w + 2) / 3.6
If walking speed changes from 1.0 m/s to 0.8 m/s, how does the equation change?
That is quite an important piece of information.
When technical writing leaves out the crucial bit
What has probably happened is that, back in the distant past, someone wrote a whole long explanation of the equation: how it worked, how it was derived, how all the parts affected each other, and what was actually going on.
Then someone else came along and decided that the massive explanation was boring.
And, to be fair, they were probably right. It probably was boring.
Long explanations are not always thrilling. And most of the time, we do not need to know exactly how an equation was derived in order to use it.
But in cutting out all the “boring” bits, they also managed to cut out the bit we actually needed.
Which is less ideal.
Why complete information matters in technical documents
This is a classic technical writing problem. A formula may look complete, but if the supporting information is missing, the reader cannot use it properly.
That is where good editing services and professional technical writing services make a real difference. In technical documents, it is not enough for the equation to be present. The document also needs to explain any conditions, assumptions or variable changes clearly enough that the reader can actually apply it.
Otherwise, you are left with a formula that appears helpful, but becomes oddly mysterious the moment anything changes.
Missing context makes equations harder to use
This sort of issue comes up often in technical writing.
An equation, table or instruction is trimmed down for clarity. Everyone is pleased because the document is now shorter and cleaner. But somewhere along the way, a key piece of context disappears, and nobody notices until a reader tries to use the information in a slightly different situation.
For a professional editor in Melbourne, or anywhere else, this is exactly the kind of thing worth checking carefully. If a document tells readers to adjust one variable, it also needs to tell them what effect that adjustment has on the formula, calculation or result.
What should you do?
Go through all your equations carefully.
Make sure that anyone using them will have all the information they need about how to use them.
Not just the equation itself, but also:
- what each variable means
- what assumptions the equation is based on
- what happens when those assumptions change
- whether the formula still applies in special cases
Because if the document says the walking speed changes, it should not then leave the reader to perform interpretive dance in order to work out what happens next.
