Re: Do you want it?


Greg Heath wrote:
Reef Fish wrote:
Greg Heath wrote:
Reef Fish wrote:

I think Greg's attention span is good only for a few lines. So, I'll
snip all except those few line:

I think the emphasis in a "sample variance" is that it is obtained from
a SAMPLE of data values. The criterion of estimation does not
alter the fact that they are all called "sample variance", as a short
for of "sample estimate of the population sigma under criterion #".

What modifications to above discussion result when the population
mean, M, is known and the unbiased estimate for the covariance
matrix is

S = Sum(Xi-M)(Xi-M)'/N ?

Hope this helps.

You should snip that line from your sig file. What you post seldom
helps anyone.

That's debatable.

In this case, you're asking a question that is already
answered.

I inferred that it had been answered. However, I can't find where it
had been directly asked. Therefore I made it a point to get a direct
answer to a direct question. In particular,

"Does any part of the sample variance discussion change when
the population mean is used instead of the sample mean?"

Simple direct question asked.

Simple direct answer expected, i.e., either "No" or "Yes, because ...".

A bit too advanced for you to figure out the logic, isn't it, that the
answer is "NO" ?

You S came from a SAMPLE didn't it?

Of course. However, that's not the point. See the word SAMPLE?

But that WAS the whole point. I even had the whole post trimmed down
to 4 lines so that even with your short attention span you wouldn't
miss
the point:

I think the emphasis in a "sample variance" is that it is obtained from
a SAMPLE of data values. The criterion of estimation does not
alter the fact that they are all called "sample variance", as a short
for of "sample estimate of the population sigma under criterion #".

So, what's the relevance of the unbiased estimate of the
covariance in your question?

An equation with M instead of Xbar for clarification.

Makes no difference in calling it a SAMPLE variance as long as it is
computed from a SAMPLE. The M or unbiasedness are irrelevant.

RF says to Greg the slow learner > Hope this helps.

Greg

You and Luis A. Afonso should make a good team.

-- Reef Fish Bob.

.

Relevant Pages

  • Re: Do you want it?
    ... I think Greg's attention span is good only for a few lines. ... The criterion of estimation does not ... alter the fact that they are all called "sample variance", ... You should snip that line from your sig file. ...
    (sci.stat.math)
  • Re: Do you want it?
    ... alter the fact that they are all called "sample variance", ... mean, M, is known and the unbiased estimate for the covariance ... You should snip that line from your sig file. ... Simple direct question asked. ...
    (sci.stat.math)
  • Re: Do you want it?
    ... "Now consider the sample variance, ... RF> some estimation criterion. ... RF> For (N-1), # = Unbiased Estimate. ... mean, M, is known and the unbiased estimate for the covariance ...
    (sci.stat.math)
  • Re: Do you want it?
    ... Jack Tomsky wrote: ... "Now consider the sample variance, ... RF> some estimation criterion. ... RF> For (N-1), # = Unbiased Estimate. ...
    (sci.stat.math)