“in the non-rigorous way” vs. “in a non-rigorous way”

Question

I answered a question just now, where I said

Actually, you are calculating the false positive rate (FPR) instead of the false positive, it seems that wiki example uses this term in the non-rigorous way.

I am concerned I misuse the expression, so, "in the non-rigorous way" or "in a non-rigorous way", which one is idiomatic?

If you have a more idiomatic and clear expression about this, please let me know.

Answer 1

If there were only two choices, one specific rigorous method and one specific non-rigorous method, then the definite article (the) makes sense.

However, since there are many ways to not be rigorous (e.g. sloppy measurements, using uncalibrated tools, failure to have a control, etc.), then the indefinite article (a) would apply.