2020-10-19

Why is it always "percentage"?

I got a side assignment at work Friday: write a test harness and tests for a pieces of software a colleague is writing.

This is suppose to be a reference implementation, so having different people write the code and the tests is a good idea: it will tend to expose ambiguities in the specification and unstated assumptions in the implementations.

"No problem," I said, "but I'll need a copy of the spec."

As I'm reading the spec today I come to:

The input value, given as a precentage in decimal format (a value between zero and one)

Sigh.

Now, there is a strict reading in which this is technically correct, but that reading conflicts with the lay uage of "percentage" in a way that leaves room for ambiguity. The parenthetical clause is necessary to resolve the ambiguity. In the tradition of academic physics we'd have written "The input value, given as a fraction" explicitly because there is no chance that it will be misinterpreted.

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