I understand that if you're speaking a phrase in which you would write parentheses, you can say the word parenthetically. But when should you write the word parenthetically?
I came across this sentence, starting off a paragraph in a scientific article:
Parenthetically, we note that subjects in all experimental conditions were unbiased …
This struck me as odd. If they're speaking parenthetically, shouldn't it be in parentheses? On the one hand, from a descriptive point of view, the usage of the word was not ambiguous – I know exactly what the author is trying to connote by using it. But from a prescriptive point of view, would this be considered proper grammar?