Hello,
I am running a few simulations for clinical trial anlysis. I want some help
regarding the following.
We know trhat as the sample size increases, the variance should decrease, but
I am getting some unexpected results. SO I ran a code (shown below) to check
the validity of this.
Hello,
I am running a few simulations for clinical trial anlysis. I want some help
regarding the following.
We know trhat as the sample size increases, the variance should decrease, but
I am getting some unexpected results. SO I ran a code (shown below) to check
the validity of this.
The variance of Xbar decreases as 1/n; the sample variance
of X does not.
- tom blackwell - u michigan medical school - ann arbor -
On Tue, 19 Aug 2003, Padmanabhan, Sudharsha wrote:
I am running a few simulations for clinical trial anlysis. I want some help
regarding the following.
On 08/19/03 17:42, Padmanabhan, Sudharsha wrote:
Hello,
I am running a few simulations for clinical trial anlysis. I want some help
regarding the following.
We know trhat as the sample size increases, the variance should decrease, but
I am getting some unexpected results. SO I ran a code
exactly using basic math stat, BTW.
Andy
-Original Message-
From: Padmanabhan, Sudharsha [mailto:[EMAIL PROTECTED]
Sent: Tuesday, August 19, 2003 1:43 PM
To: [EMAIL PROTECTED]
Subject: [R] Variance Computing- - HELP!!
Hello,
I am running a few simulations
I think you are confused. As sample size increases, the variance of an
estimate based on that sample will decrease asymtotically to zero (e.g.,
the standard error of the mean will go to zero). However the variance of
the sample itself will not change. Any difference you see in your data
is simply
Perhaps you were trying for as sample size increases, variance *of the
mean* decreases (a least when variance is finite). If you swap mean and
var in your code, I think you will get what you are looking for.
-- Tony Plate
At Tuesday 05:42 PM 8/19/2003 +, Padmanabhan, Sudharsha wrote:
: Padmanabhan, Sudharsha [mailto:[EMAIL PROTECTED]
Sent: Tuesday, August 19, 2003 1:43 PM
To: [EMAIL PROTECTED]
Subject: [R] Variance Computing- - HELP!!
Hello,
I am running a few simulations for clinical trial anlysis. I want some help
regarding the following.
We know trhat
Padmanabhan, Sudharsha [EMAIL PROTECTED]
We know trhat as the sample size increases, the variance should
decrease,
Should it?
I can paraphrase his test case thus:
v100 - sapply(1:100, function(i) var(rnorm(100, 0, 3)))
# We expect the elements of v100 to cluster
