Date:         Wed, 28 Jul 1999 14:55:35 -0400
Reply-To:     Donna Barre <dbarre@DOE.STATE.VT.US>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Donna Barre <dbarre@DOE.STATE.VT.US>
Subject:      Apparent Rounding Problem
Comments: To: "SPSSX-L@UGA.CC.UGA.EDU" <SPSSX-L@UGA.CC.UGA.EDU>
Content-Type: text/plain; charset=us-ascii

My colleagues and I have been using the Tables module and the crosstab
procedures.  When the figures in the tables are examined there are many
instances (10% or more) where the totals do not round to 100%.
Relatedly, when an individual cell in the output is viewed, it initially
contains one value, say, 62.  When the actual number in the cell is
selected, it contains a number such as 62.5001.  When the cursor is
moved out of the cell, the number changes to 63.

My question:  Is there a way to change the way rounding occurs in
SPSS,or is this a bug? And, if it is a bug, does it affect only "simple"
procedures such as crosstabs and similar calculations in Tables, or does
it affect all calculations?  Does SPSS use double precision in
performing calculations, and if not, is this the origin of the rounding
problem?

Reporting numbers to the public that can readily be seen as inexact by
anyone who does the arithmetic harms the credibility of a state agency.
Thank you for any help and insights you can give me on this issue.

Donna M. Barre, PhD
Statistician, VT Dept of Education