Date:         Tue, 5 Jan 2010 11:07:22 -0500
Reply-To:     "Keintz, H. Mark" <mkeintz@WHARTON.UPENN.EDU>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Keintz, H. Mark" <mkeintz@WHARTON.UPENN.EDU>
Subject:      Re: New Comparison Operators? - WAS: missing numerical values = -
Comments: To: Lou <lpogoda@HOTMAIL.COM>
In-Reply-To:  <hhve12$9e$1@news.eternal-september.org>
Content-Type: text/plain; charset="us-ascii"

Lou said:

> -----Original Message-----
> From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
> Lou
> Sent: Tuesday, January 05, 2010 8:15 AM
> To: SAS-L@LISTSERV.UGA.EDU
> Subject: Re: New Comparison Operators? - WAS: missing numerical values
> = -
>
> "Jonathan Goldberg" <jgoldberg@BIOMEDSYS.COM> wrote in message
> news:201001042207.o04BkhjO010396@malibu.cc.uga.edu...
> >I gave an (and who knows, maybe the) explanation in a post on the old
> > thread before I noticed this new one.  For ease of reference, here it
> is
> > again.
> > ---------------------------------------
> > This is a hoary question.  Logically speaking, having x < 2500
> resolve to
> > true when x is missing is absurd, and having x = y resolve to true
> when
> > both x and y are missing is ludicrous.  Missing means "I don't know."
> If
> > x and y are heights, you are claiming that you know that two heights
> are
> > equal when you don't know what either of them is.
>
> At the risk of seeming the fool, I've always thought of it as:
>
> if X = "I don't know" and y = "I don't know" then x does equal y.


Lou:

That is a research or analysis issue, and is context sensitive.

For many SAS users, it is not simply a question of mathematical logic.


Regards,
Mark