Re: Idempotence and "Replication Insensitivity" are equivalent ?

vc ha scritto:

> pamelaflue..._at_libero.it wrote:
> > vc ha scritto:
> > Since we are here (cdt), they could be the values that you find in the
> > records
> > for a given field. For instance, your records are variables observed on
> >
> > your students and the field of interest could be the number of members
> > of their family. You could be interested in the Median family size *of
> > your
> > students*... You could be interested in other statistics as well, Mean,
> > std, etc. ...
>
> OK, so you are saying that the collection {1,2,3} is in fact a random
> sample realization, let's say the number of children in a family,
> which leads us to the original question. What grounds do you have for
> stating that having one, two or three children is equally probable ?
> You visited three households and are now trying to extrapolate your
> experience for say the entire city ?
>

You insist with the random sample story.

Forget about random samples.

I have 4 students not belonging to the same family and I want to know *their* median
family size { 1 5 2 7 }. I do not want to make inference about the whole world. Just interested in *that* set. They do not represent, to me, any other set in which they are contained. That set is all my word, and I want to describe only that set. The whole population is know.

Is it clear? There is no inferential aim. Only description. That's why it's called *Descriptive Statistics*. You are talking of another branch of statistics: Statistical Inference.

I repeat. I am saying that computing the median of { 1 5 2 7 }

• is like *

computing the median of a discrete random variable X that takes the values 1,5,2,7 each with probability 1/4.

What do find hard to get in this *analogy* ? Received on Tue Sep 26 2006 - 22:16:56 CEST