# Thread: tending to infinity of standard deviations

1. ## tending to infinity of standard deviations

hi guys,

i have a question puzzling me:

if x tends to infinity based on some function (where x is a number) ,
does it imply that the standard deviation of x tend to Zero ?

cheers,
joey

2. ## Re: tending to infinity of standard deviations

I don't understand what you're saying?

You say "where x is a number" but then you talk about the standard deviation of x - which implies x is either a random variable or a vector of results. Can you reword what you're trying to say?

3. ## Re: tending to infinity of standard deviations

hi dason,

this is true, x is a vector with a standard deviation. It is infact a 2D coordinate position.

So, I have :

x = [ 20 ; 34555] +/- 255
where 255 is the standard deviation.

Now,I know that my vector x tends to infinity and I am getting a rather large standard deviation for it, which I think means that there is high uncertainty associated with 'x' (or at least this is what I assume ,not 100% sure on that).

Can I make the assumption that if x tends to infinity , then its standard deviation(i.e.precision) will tend to zero?

cheers
Joe

4. ## Re: tending to infinity of standard deviations

Without knowing more or making additional assumptions I don't see how you could assume that.

Also note that precision is 1/standarddeviation which might be what's causing part of my confusion with your problem. You keep saying that the standard deviation grows as x gets large and then you say that you want to make the claim that the standard deviation goes to 0 as x gets large - which contradicts what you previously said...

5. ## Re: tending to infinity of standard deviations

Dason,

I will ask something more straightforward.

If x tend to Inf
is it correct to imply Std_dev_of_x also tend to Inf ?

cheers

6. ## Re: tending to infinity of standard deviations

Once again... Without knowing more or making additional assumptions I don't see how you could assume that.

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