## anonymous 4 years ago Mathematical statistics question. Under what conditions does the function $$f\left(x_1,x_2,\ldots,x_n\right)$$ have the error:$\sigma_f=\sqrt{\left(\frac{\partial}{\partial x_1}f\sigma_{x_1}\right)^2+\left(\frac{\partial}{\partial x_2}f\sigma_{x_2}\right)^2+\ldots+\left(\frac{\partial}{\partial x_n}f\sigma_{x_n}\right)^2}$

1. anonymous

Notably the delta method http://en.wikipedia.org/wiki/Delta_method#Note mentions this, alongside what looks like gradient functions. $$\sigma_f$$ resembles the magnitude of a gradient, but that's not inclusive of variance. So, in other words, I have no idea what's going on.

2. NotTim

Me too. I have connections with people who do statistics, and I've done a little data management myself, but I don't know about this. Similar format to what I know, but...

3. anonymous

At this rate I'll never be in analysis research. :( That's okay, though. I'm fine with being a student forever.

4. NotTim

Uhh..Sorry.

5. NotTim

None of the really good people are online I think. I'll ask around.

6. anonymous

I don't go around apologizing for everything I can't do; I don't see why you are.

7. NotTim

I usually come, answer, and then the person goes away understanding the question. But that hasn't happened here.

8. anonymous

I usually read the textbook and learn something new, but that hasn't happened here either. XD These things are out of my control. The best I can do is correct for it, but I'm definitely not apologizing for it.

9. NotTim

Hey, sorry about not be able to help. Post a link in the chats occasionally. Maybe a good person will see it.

10. anonymous

Is it against etiquette to just repost?

11. anonymous

@myininaya @across @satellite73 can any of you help with this? Or know who can?

12. NotTim

They're HERE??

13. anonymous

Yes, noradetzky, it is. However, hopefully someone will see this tomorrow. The weekend is usually kinda dead around here.

14. anonymous

No, but they are at least pinged now. I don't ping them very often, so this will probably catch their attention.

15. NotTim

@LagrangeSon678 @mertsj @zarkon @jim_thompson5910 @Chlorophyll Please help? Man. Feels like I'm calling up powerful unholy forces. Nice.

16. anonymous

I hope the users here aren't accurately described by "powerful" and "unholy". ;D

17. NotTim

err...I was being figuratively. Please that statement be figurative and not Literal.

18. NotTim

that being literal....ugh.