Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Re[2]: Minitab's outliers
Replies: 0

 Search Thread: Advanced Search

 Pat Ballew Posts: 356 Registered: 12/3/04
Re[2]: Minitab's outliers
Posted: Sep 25, 1996 2:00 PM
 Plain Text Reply

Peter,
First, thanks for your reply. This has me really wondering about
how the guys out in the world use the terms. I thought I understood
what was the common usage, and now I am totally unsure. I would like
to at least know that I'm preparing my students with language
appropriate for the AP exam.
I guess I can see a logic to your definition of median as a range
of values for some situations but,I thought the definition was fairly
consistant, at least I'm satisfied that the way I teach it my students
will be able to communicate with other people in the field
successfully. I do think it is a little confusing if you apply the
range of values idea to percentiles . If I were to tell you I
interviewed three people and 50% of them were male, I think your first
reaction would be to look at me somewhat suspiciously. I feel much
the same discomfort in saying that the 50th percentile of (0,0,1) was
0. It is true that 50% of the ordered data were at or below this
value, and 50% were at or above this value, but then I could say the
same thing for any value from 34 to 66.

I guess I'm more concerned about having my students able to
understand what is meant when it is written in common statistical
usage but I would like (hope) for that usage to be as common and
mathematically reasonable as possible.

Pat Ballew
Misawa, Japan

______________________________ Reply Separator _________________________________
Subject: Re: Minitab's outliers
Author: Peter Blaskiewicz <pjb@mcc.cc.tx.us> at EDU-INTERNET
Date: 9/24/96 12:20 PM

One of my esteemed statistics teachers in college several years ago
defined the median for us as a value that is chosen/calculated in such
a way that
1) at least 50% of the ordered data was at or below that value, and
2) at least 50% of the ordered data was at or above that value.

He extended this definition in a natural way to cover percentiles also.

Note that, under this definition, it is not necessary that there be a
unique median for a given set of data. For example, in the data set
{0,1}, every number in the closed interval from 0 to 1 would qualify as
a median. However, when we accepted this as our working definition
of median, it helped us resolve many problems.

Peter Blaskiewicz

© The Math Forum at NCTM 1994-2018. All Rights Reserved.