One reference for the construction is J.L Devore, Probability and
Statistics. 1995. 4th Edition. Duxbury Press, Boston MA. I came across it
as the "Box plot Rule" in a biotech industry publication (Panvera, now
defunct I believe). It was part of a discussion of methods for detecting
and handling outliers in data.
John Wallace | Research Associate | Test Method Development
AFFYMETRIX, INC. | 3380 Central Expressway | Santa Clara, CA 95051 | Tel:
408-731-5574 | Fax: 408-481-0435
-----Original Message-----
From: S�ren O'Neill [mailto:[email protected]]
Sent: Tuesday, July 06, 2004 10:31 AM
To: [email protected]
Subject: Re: st: Box and whiskers graph
Thanks ... my wife says I have no imagination :-)
Your comments are most useful and pretty much answer my question ... thanks!
Soren
On Tuesday 06 July 2004 19:21, Marcello Pagano wrote:
> Oops, that should read 99.2%, not 99.7% .
>
> m.p.
>
> Marcello Pagano wrote:
> > What Ted said is quite correct, but you can also exercise your
> > imagination and notice that if you have normal data, then the expected
> > value of the interquartile range is 1.34 sigma (just reading from the
> > normal tables). Thus, in this case, the adjacent values are estimates
> > of mean plus or minus twice the interquartile range, or mean plus or
> > minus 2.64 sigma. That means that you should have almost all your data
> > (99.7%) between the two adjacent values.
> >
> > m.p.
> >
> > S�ren O'Neill wrote:
> >> Thank you very much for your reply - is there a reference you can give
> >> me, that explains the reasoning behind these adjacent values -
> >> personally I rely mostly on the book Practical Statistics for Medical
> >> Research by D. Altman and I cant seem to find any reference to
> >> 'adjacent values' therein ... Also the Stata Users guide and reference
> >> manuals seem to come up short ...
> >>
> >> Kind regards
> >> Soren
> >>
> >> On Monday 05 July 2004 23:32, Ted Anagnoson wrote:
> >>> The adjacent values separate the outliers from the rest of the data.
> >>> They
> >>> are the 25th or 75th percentiles plus 1.5 times the Inter-Quartlile
> >>> range,
> >>> which is the distance between the 25th and 75th percentiles.
> >>> However, the
> >>> adjacent value indicated on the graph, by convention, is "rolled
> >>> back" to
> >>> an actual data point, so that there is always real data underneath the
> >>> adjacent value.
> >>>
> >>> So the adjacent values are not actually percentiles....but "adjust"
> >>> to the
> >>> characteristics of the data.
> >>>
> >>> Ted Anagnoson
> >>> California State University Los Angeles
> >>>
> >>> At 10:46 PM 7/5/04 +0200, you wrote:
> >>>> The box and whiskers graph illustrates the median value (with a
> >>>> line), the
> >>>> 25%
> >>>> and 75% centiles (with a box) and the adjacent values (with the
> >>>> whiskers)
> >>>> ... but what are the adjacent values? 2� and 97� centiles or ... ???
> >>>> --
> >>>> S�ren O'Neill, kiropraktor
> >>>> [email protected]
> >>>> tel. 6362 1906
> >
> > *
> > * For searches and help try:
> > * http://www.stata.com/support/faqs/res/findit.html
> > * http://www.stata.com/support/statalist/faq
> > * http://www.ats.ucla.edu/stat/stata/
--
S�ren O'Neill, kiropraktor
[email protected]
tel. 6362 1906
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
