stat: Quartile methods

[hpfx]

Hi,
as seen in wikipedia Quartile there are 3 methods to compute quartile.
bad luck, it's not the same for each national educational system...

Calculator like TI-83 (with lastest OS 5.1) allow you to choose a method.
but HP Prime only show one...

It would be nice for hpprime students to get Quartile as same as national system expect for each country.
If someone at hp company can think about that...
Thank you.

[debrouxl]

+1 on that feature request.

[Adriweb]

Indeed ; the TI-83 Premium CE just got this feature with OS 5.1, like you say, just a few days ago.
It looks like this:


(The labels could be better, like FR / US, but oh well, at least it's there )

[ThomasA]

1+ on that request, too.

[Gerald H]

Can anyone name some systems using methods 2 or 3?

[salvomic]

(09-09-2015 02:09 PM)Gerald H Wrote:  Can anyone name some systems using methods 2 or 3?

I'm curious too, please, explain us with some examples...

[cyrille de brébisson]

Hello,

Some mathematics definition are 'culture dependent'.
For example a triangle is defined in Latin country as polygon formed of 3 points. In Anglo Saxon countries as a polygon formed by 3 non-aligned points. It makes a difference.

It is the same for Quartiles.
To find quartiles, you have to first find the middle of an ordered list.
BUT how do you defined the middle of an odd sized list? multiple answers, multiple systems.
Then, you have to find the middle of the 2 sides. Well, what do you do with the middle that you already found? Do you include it in the sides or not? multiple answers, multiple definitions of Quartiles...

At this point, Prime supports the Anglo Saxon definition of Quartiles only.

Cyrille

[StephenG1CMZ]

My maths class was a long time ago, so maybe I am remembering wrongly. But I seem to recall that which definition you should use for the middle of an odd-sized list depended not on culture (which we were not aware of pre-Internet), but on application. For some applications like shoe sizes you might choose one of the two middle values. For other applications you might average them.

In the past when calculators only handled numbers it was only possible to return a numeric value - and whichever number you choose is always going to confuse someone with a different assumption or mode setting.

I would propose that the least confusing value to return on a modern calculator is not some random number depending on some probably unspecified mode setting hidden in one menu or another depending on which calculator you have. The best value to return is a list containing the two numbers of interest. A list containing two middle numbers for odd-sized lists (and for consistency a list containing one number for an even sized list).


That way there are no unexplained mode settings and no pupils getting different answers!

Once you have that list of one or two numbers visible to the pupil, the pupil can decide whether to use one or the other, or choose one at random, or calculate the average. All simple clear and explainable maths depending on the application. No hidden mode settings necessary.

[cyrille de brébisson]

cool,

here is a fourth method :-)

cyrille

[Gerald H]

(09-11-2015 05:14 AM)cyrille de brébisson Wrote:  cool,

here is a fourth method :-)

cyrille

Where?

Excel uses method 2 from the Wikipedia article, no alternative & no detailed explanation.

[DrD]

The G1CMZ proposal...

excel, another calculator, another method. Cyrille's point.