Web Images Maps News Groups Books Gmail more »
Recently Visited Groups | Help | Sign in
Google Groups Home
variance and convergence in distribution
There are currently too many topics in this group that display first. To make this topic appear first, remove this option from another topic.
There was an error processing your request. Please try again.
flag
  2 messages - Collapse all  -  Translate all to Translated (View all originals)
The group you are posting to is a Usenet group. Messages posted to this group will make your email address visible to anyone on the Internet.
Your reply message has not been sent.
Your post was successful
 
From:
To:
Cc:
Followup To:
Add Cc | Add Followup-to | Edit Subject
Subject:
Validation:
For verification purposes please type the characters you see in the picture below or the numbers you hear by clicking the accessibility icon. Listen and type the numbers you hear
 
Yihong  
View profile  
 More options Nov 5, 8:59 am
Newsgroups: sci.math
From: Yihong <yihon...@princeton.edu>
Date: Wed, 04 Nov 2009 19:59:45 EST
Local: Thurs, Nov 5 2009 8:59 am
Subject: variance and convergence in distribution
Dear all,

I have a question as follows: we know that convergence in distribution does not imply convergence of moments. In fact by Fatou's lemma and Skorohod's representation, if X_n -> X in distribution, we have

liminf E[X_n^2] >= E[X^2]

and strict inequality is possible, e.g., consider P{X_n = 0} = 1-1/n and P{X_n = n} = 1/n, X_n -> 0 in distribution.

Now, how about variance? My question is that is it possible to construct an example such that X_n -> X in distribution and

liminf var X_n < var X < Infinity?

Clearly this could happen only when E[X_n^2] is unbounded.

Thanks!
YH


    Reply    Reply to author    Forward  
You must Sign in before you can post messages.
To post a message you must first join this group.
Please update your nickname on the subscription settings page before posting.
You do not have the permission required to post.
Ken Pledger  
View profile  
 More options Nov 6, 3:37 am
Newsgroups: sci.math
From: Ken Pledger <ken.pled...@mcs.vuw.ac.nz>
Date: Fri, 06 Nov 2009 08:37:55 +1300
Local: Fri, Nov 6 2009 3:37 am
Subject: Re: variance and convergence in distribution
In article
<157660423.12726.1257382815175.JavaMail.r...@gallium.mathforum.org>,

 Yihong <yihon...@princeton.edu> wrote:

> .... we know that convergence in distribution does
> not imply convergence of moments....

     You may have better luck with your question in the <sci.stat.math>
news group.

           Ken Pledger.


    Reply    Reply to author    Forward  
You must Sign in before you can post messages.
To post a message you must first join this group.
Please update your nickname on the subscription settings page before posting.
You do not have the permission required to post.
End of messages
« Back to Discussions « Newer topic     Older topic »

Create a group - Google Groups - Google Home - Terms of Service - Privacy Policy
©2009 Google