[Openspace] quantile plot

[Darla Munroe]

Michael - see Luc's message from yesterday - the first two quantiles were "too close to call" - so it grouped them together, and YES this is in the manual - read it closely - one of my students found the exact paragraph last semester.

----- Original Message -----
From: Michael Anyadike-Danes <m.anyadike-danes at qub.ac.uk>
Date: Tuesday, September 21, 2004 0:37 am
Subject: RE: [Openspace] quantile plot

> Julia
> 
> Thanks for your suggestion but ...
> 
> 1. the data is expressed as a rate in this case
> 2. there are just a handful of real outliers (1 or 2) at each end
> 
> Is the procedure for determining the 'breakpoint' described 
> anywhere? 
> 
> Michael
> 
> 
> 
> -----Original Message-----
> From: Julia Koschinsky [koschins at uiuc.edu] 
> Sent: 20 September 2004 23:08
> To: Michael Anyadike-Danes
> Cc: Openspace at Agec221. Agecon. Uiuc. Edu
> Subject: RE: [Openspace] quantile plot
> 
> Michael,
> 
> One of the reasons why you can end up with different numbers of
> observations
> in your quintile categories is if you are using count data that is
> skewed,
> for instance has a lot of zeros or small numbers (as is the case with
> certain mortality or risk data). In those cases, the computation of
> break
> points is unreliable because there are ties between the frequently
> occurring
> values. The use of rates instead of counts is more appropriate here.
> 
> Please write back if this does not address your problem.
> Julia
> 
> ******************************************
> Julia Koschinsky
> Spatial Analysis Laboratory
> University of Illinois at Urbana-Champaign
> http://sal.agecon.uiuc.edu
> 
> 
> -----Original Message-----
> From: openspace-bounces at agec221.agecon.uiuc.edu
> Behalf Of Michael Anyadike-Danes
> Sent: Monday, September 20, 2004 10:32 AM
> To: openspace at agec221.agecon.uiuc.edu
> Subject: [Openspace] quantile plot
> 
> 
> I have a dataset with 434 observations.
> 
> I requested a quantile map with 5 divisions (ie a quintile map).
> 
> The map has five divisions: "1st range (0); 2nd range (165); 3rd range
> (87);
> 4th range (95); 5th range (87)".
> 
> I was expecting 5 more-or-less equal ranges (86 and/or 87).
> 
> Have I missed something?
> 
> Michael Anyadike-Danes
> Economic Research Institute of Northern Ireland
> 
> 
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