Hi martin

I have 115,000 odd results with about 960 total combinations of variety and soil. Thats a lot of selections. Would prefer to do it more directly if there is a way.

r

On Tue, 8 Mar 2005 13:29:33 +1100, Martin Higham <[EMAIL PROTECTED]> wrote:

Hi Robert,

For each class (ie. combination of soil and variety) you need to order the
production values, then select the 75th percentile value - ie. for ascending
sort, get the production value for RowID = Total Rows*3/4.


This is of course trivial - the complication comes in that you need to
create a separate sorted selection for each class. Easy to do manually, but
if you've got a lot of classes, could be prone to error.



Best Regards,

Martin Higham
Avantra Geosystems

ph (61 3) 8504 0428   0425-730-428
fx (61 3) 9596 7997
www.avantra.com.au




-----Original Message-----
From: Robert Crossley [mailto:[EMAIL PROTECTED]
Sent: Tuesday, 8 March 2005 13:26
To: MapInfo List
Subject: MI-L top 25% query



Hi,

I have a table of data that gives me the amount of product produced for
paddocks, and each paddock has a soil and variety attribute.  I
am trying
to work out how to get a query that will give me the production
level that
is equivalent the top 25% (or 10%) of paddocks produced for each
combination of soil and variety.

I suspect that I could do this with some statistical functions,
but am not
sure - been about 20 years since I did stats - and can't find
reference to
a std dev function in the manual, but perhaps there is a better way.

Any suggestions - and it is being done in Mapbasic.

Thanks
r


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-- ________________________________________________

Robert Crossley

Agtrix P/L
9 Short St
PO Box 63
New Brighton 2483
Far Southern Queensland
AUSTRALIA

153.549004 E 28.517344 S

P: 02 6680 1309
F: 02 6680 5214
M: 0419 718 642
E: [EMAIL PROTECTED]
W: www.agtrix.com
W: www.wotzhere.com
skype: robertcrossley

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