Each field seems to have its own nomenclature. I recognize 'instrumental variables' from a (bio-)statistics course, so I think that's a pure statistics term. Larry Wasserman has a vocabulary chart in 'All of Statistics' (there's a PDF I won't link to) that lists terms differing between statistics and computer science. For example he writes that 'using data to estimate an unknown quantity' is called 'estimation' in statistics and 'learning' in computer science.

I'm a trained a econometrician and a data scientist. Have you found people to be apprehensive with you since 'our' verbiage is different?

Is that what I asked?

I'm asking about why the usage of the mathematics that you and I are apparently both familiar with could be described in different ways depending on which field is referencing it. This is a linguistic question - not a mathematical one.

No need to be rude.

Is that what they asked?

Nomenclature is different in different fields all the time, or even different areas of the same field. It all depends on what practitioners feel is most intuitive.

No need to call someone rude for not answering your question and asking their own instead.

What was rude? A question?