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Date:         Fri, 18 Dec 1992 14:12:00 EST
From:         dkw4@NIOSHE2.EM.CDC.GOV
Subject:      Re: Tutorial Software (fwd)

I forwarded J. Philip Miller's comments about the dangers of using
spreadsheet packages with ill-conditioned data to some of the industrial
hygienists I work with.  What follows is a response from one of them.

Dr. Miller, could you answer these questions directly if you've got the
time/energy?  If not, I'll take my own best stab 'cause I tend to concur
with your opinion.   I'd also be happy to hear from anyone else on this.

Thanks very much -

Deanna Wild

*-----------------------------------------------------------------*
Deanna Wild
Statistician
National Institute for Occupational Safety and Health
4676 Columbia Parkway  MS: R-4
Cincinnati, Ohio  45226

INTERNET: DKW4@NIOSHE2.EM.CDC.GOV
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FORWARDED FROM: Wild, Deanna K.
FROM: Zaebst, Dennis D.

TO:  dkw4 CINC/NIOSHE2                                        DATE:  12-18-92
                                                              TIME:  12:21
CC:  Hines, Cynthia J.
     Kawamoto, Melody M.
     Waters, Martha A.
     Zaebst, Dennis D.

SUBJECT:   Re: Tutorial Software (fwd)
PRIORITY:  R
ATTACHMENTS:

Deanna:

I hope I'm not stirring up a hornet's nest, but here goes...

Can you explain any of the background, or expand on exactly what Dr. Miller
is saying?

As one who has used Lotus, and subsequently, Quattro Pro and Excel for
straightforward statistics for years, I am a little perplexed by this guy's
response that teaching students to do statistical analyses on a spreadsheet
is "worrisome".  Is he saying that, specifically, using the multiple
regression routines in spreadsheets gives inaccurate results?  Does he have
data which demonstrate this?  What does he mean by "ill-conditioned data"?
If the results are inaccurate, how inaccurate are they?  When should they be
avoided, or should they never be used?

By the way, have you looked at the list of statistical functions and
commands built into Excel 4.0?  All I can say is, WOW!  But can we use them
safely?

I guess the issue boils down to how well tested is the software under a wide
variety of situations (data sets and analyses)?  Is SAS better tested than
Quattro Pro, Excel, or for that matter, Statgraphics, SPSS, S-plus, or CSS
Statistica?  What do we really know about the comparative accuracy of
results?  I would think that the accuracy would partly depend on the software
itself, but we also have to remember that all these programs are running on
the same microprocessor with the exact same instruction set built into it
(80x86).

Is this a really serious issue, or are these people splitting hairs about the
15th decimal place, or something in between?  (Can we get Dr. Miller to
respond directly to the above questions)?

Sorry about all the questions.   Just what you need just before the holidays,
eh?

Thanks,

Dennis Z.
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 REPLY FROM: Zaebst, Dennis D. FROM: Wild, Deanna K.

TO:  Kawamoto, Melody M. CINC/NIOSHE1                         DATE:  12-11-92
     Sussell, Aaron L. CINC/NIOSHE1                           TIME:  15:13
     Zaebst, Dennis D. CINC/NIOSHE1

CC:
SUBJECT:   Re: Tutorial Software (fwd)
PRIORITY:  R
ATTACHMENTS:

Just one additional comment (from a statistical discussion group on Internet)
about using spreadsheets to do statistical analyses...  It showed up today
and seemed too coincidental to ignore...

Deanna

------------------------------------------------------------------------------
FORWARDED FROM: Wild, Deanna K.
DATE: Dec 11 04:08:29 1992 -00:00 relative to GMT
FROM: "J. Philip Miller" [A=ATTMAIL; S=Miller"; G="J.; I="P; DDA.TYPE=ID; DDA.
      VALUE=internet(b)WUBIOS.WUSTL.EDU(b)phil]

SUBJECT: Re: Tutorial Software (fwd)
IPMessageID: internet3460408260

TO: Multiple recipients of list STAT-L [A=ATTMAIL; S=STAT-L; G=Multiple; I=Mr;
     DDA.TYPE=ID; DDA.VALUE=internet(b)VM1.MCGILL.CA(b)STAT-L]

PRIORITY:
> In article <9212100544.AA23083@leven> brobinso@LEVEN.APPCOMP.UTAS.EDU.AU
> writes:
> >Wot about a simple spreadsheet? All you have to do is get them to set up
> >the required columns and program the formulae. I haven't seen a spreadsheet
> >yet that does regression and correlation, even though nearly all have mean
> >and SD.
>
> I think using a spreadsheet is a very good suggestion, but I'm a little
> perplexed by the last sentence:  123 has done multiple regression in every
> version I've used, as has Quattro Pro.  They don't do them via @ functions,
> instead they're there as commands.  In Quattro Pro 1.0 it's in the Tools
> Advanced Math menu.  I forget where 123 put it, and don't have recent
> versions of either package to look at.

I don't want to open up a heated discussion that was previously held here, but
I feel I must point out that many of us who specialize in computational
statistics have some problems with this.  The primary reasons for this is that
the "obvious" formulae are problematic with respect to numerical accuracy for
ill conditioned problems.  Thus the idea that we should teach students to do
something which may result in wrong answers is worrysome.

-phil

--
     J. Philip Miller, Professor, Division of Biostatistics, Box 8067
         Washington University Medical School, St. Louis MO 63110
     phil@wubios.WUstl.edu - Internet  (314) 362-3617 [362-2694(FAX)]
Newsgroups: bit.listserv.stat-l