## noradetzky 3 years ago Mathematical statistics question. Under what conditions does the function $$f\left(x_1,x_2,\ldots,x_n\right)$$ have the error:$\sigma_f=\sqrt{\left(\frac{\partial}{\partial x_1}f\sigma_{x_1}\right)^2+\left(\frac{\partial}{\partial x_2}f\sigma_{x_2}\right)^2+\ldots+\left(\frac{\partial}{\partial x_n}f\sigma_{x_n}\right)^2}$

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...

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.

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.

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.

Is it against etiquette to just repost?

11. Laura*

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

12. NotTim

They're HERE??

13. Laura*

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

14. Laura*

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.

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.