I think the implication of getting worse is strong enough that (outside the technical uses in statistics) you’d never say “regress” when the change involved wasn’t a worsening. E.g., if I try to imagine any of the following, I can’t see anyone actually saying them. “I have good news for you: the latest scans show that your cancer has regressed somewhat.” “The fifth wave of the COVID-19 pandemic is beginning to regress now.” “The most recent figures show some regression in the unemployment caused by last year’s financial crash.”
The statistical uses—“regression to the mean” and the practice of “regression” (meaning model-fitting), which historically is actually derived from “regression to the mean”—are of course well enough established that once you’re used to them they don’t carry any connotation of things getting worse.
[EDITED to add:] On looking in the OED, I find that in fact “regression” is used about tumours and the like. But I bet that in the unfortunate event that any of us has to consult an oncologist, they will not use the word in that sense with us; I think it’s for technical use only, just like the statistical sense.
Ah, this makes a lot of sense. Good examples. In looking at those examples, it does seem clear to me that my original impression about what it means in the context of everyday life was correct.
I think the implication of getting worse is strong enough that (outside the technical uses in statistics) you’d never say “regress” when the change involved wasn’t a worsening. E.g., if I try to imagine any of the following, I can’t see anyone actually saying them. “I have good news for you: the latest scans show that your cancer has regressed somewhat.” “The fifth wave of the COVID-19 pandemic is beginning to regress now.” “The most recent figures show some regression in the unemployment caused by last year’s financial crash.”
The statistical uses—“regression to the mean” and the practice of “regression” (meaning model-fitting), which historically is actually derived from “regression to the mean”—are of course well enough established that once you’re used to them they don’t carry any connotation of things getting worse.
[EDITED to add:] On looking in the OED, I find that in fact “regression” is used about tumours and the like. But I bet that in the unfortunate event that any of us has to consult an oncologist, they will not use the word in that sense with us; I think it’s for technical use only, just like the statistical sense.
Ah, this makes a lot of sense. Good examples. In looking at those examples, it does seem clear to me that my original impression about what it means in the context of everyday life was correct.