Date:         Fri, 16 Nov 2001 10:48:38 -0500
Reply-To:     "Dorfman, Paul" <Paul.Dorfman@BCBSFL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Dorfman, Paul" <Paul.Dorfman@BCBSFL.COM>
Subject:      Re: A RETAIN Oddity
Comments: To: John Whittington <John.W@MEDISCIENCE.CO.UK>
Content-Type: text/plain; charset=iso-8859-1

> If you regard a DATA step as a 'black box', which you are allowed to
> investigate by adding 'explicit' PUT statements (i.e. ones
> actually naming vars, not _all_ etc.), if the PUT statement(s) return
missing
> values, then you have learned nothing about whether or not the vars in
> question were in the PDV _in the absence of_ the PUT statement.  The
'probe'
> has altered that which it is 'probing'!

John,

It is a keen observation, really invoking the reminder of the Heisenberg's
Principle...

Kind regards,
====================
Paul M. Dorfman
Jacksonville, Fl
====================


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