Hello, The original question from Michael is:
Is there a SQL function available for finding the median value from a column of numbers? I see AVG() but no reference to medians. Thanks. Does the sql AVG() skip ruled out values by some non-parametric test? Every SQL description of AVG() at my disposal does not discuss non-paramteric tests or ruled out values. Can we assume that if sql had a MEDIAN() it would not be any more conditioned than the AVG() function? Is the column of numbers a series of samples? If so is the median of these samples what you want? What is your goal? What is the situation of your data? Are you comparing medians from different number series where the populations have different shapes? Then neither means nor variances nor medians may provide the proper comparative measures; and then nonparametric methods come into play. But if the shapes of the populations are similar why complicate matters and make your data analysis operation system dependent? On the other hand, from rereading our discussion I believe Sinisa (and he may confirm this) is correct in cautioning against implementing a median based on its definition(which is correct) as I suggested and not regard what you want to do with the median in context of the condition of your data. It can happen where statistical analysis is intended to work for a particular condition but eventually a user may stuff in data where the analysis will give them answers which they will use for years not knowing the underlying analysis is not using comparative measures intended for their data's condition. Eventually everybody may forget how the analysis works but use it blindly. Regards, Roger ----- Original Message ----- From: "Sinisa Milivojevic" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Saturday, December 01, 2001 9:36 AM Subject: Re: median function? > Michael writes: > > Umm does this mean there is no way to do what I need? Is it inappropiate > > to ask if it'd be difficult for such a function to be added into MySQL if > > it is the case that this is an impossible thing to do (or even just very > > challenging)? A median is a very common function to need in accounting I > > think. Thanks. > > > > > > *^*^*^* > > Michael McGlothlin <[EMAIL PROTECTED]> > > http://mlug.missouri.edu/~mogmios/projects/ > > > No, it is very easy to do. > > Add it as an UDF. This will not work on server running on Windows, > though. > > Take a look at udf_example.cc in sql/ subdir of the source. Most > notably, analyse : > > CREATE AGGREGATE FUNCTION avgcost RETURNS REAL SONAME "udf_example.so"; > > -- > Regards, > __ ___ ___ ____ __ > / |/ /_ __/ __/ __ \/ / Mr. Sinisa Milivojevic <[EMAIL PROTECTED]> > / /|_/ / // /\ \/ /_/ / /__ MySQL AB, Fulltime Developer > /_/ /_/\_, /___/\___\_\___/ Larnaca, Cyprus > <___/ www.mysql.com > > > --------------------------------------------------------------------- > Before posting, please check: > http://www.mysql.com/manual.php (the manual) > http://lists.mysql.com/ (the list archive) > > To request this thread, e-mail <[EMAIL PROTECTED]> > To unsubscribe, e-mail <[EMAIL PROTECTED]> > Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php > > --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
