Re: SPSS SPV quirk

[Ben Pfaff]

On Sun, Nov 08, 2015 at 02:42:40PM -0600, Alan Mead wrote:
> When we use modern versions of SPSS, I often scroll down to elements of
> the SPV file and that element is replaced by a message like  "Please
> wait - computing" and then after a few seconds, the content replaces
> this message.  Is this something that you've encountered and
> successfully understood?  If so, what's SPSS doing?  Is it really
> re-computing the element? That would imply that it saved all the data
> into the SPV file, which seems like an odd and potentially sensitive
> issue. I cannot say what elements do this, but I can recall seeing it
> occur for graphs.

I haven't used modern versions of SPSS, so I can't say how the user
interface behaves, but an SPV file does contain all of the data that
appears in the output.  (Otherwise it would not be possible to
distribute an SPV file independent of the SPS or SAV files.)

If I had to guess what happens when you see that message, I'd say that
it's closer to SPSS "rendering" the output element than "computing"
anything.  Because an SPV file is a fairly abstract representation of
output, something analogous to an HTML table plus CSS styling, a program
that displays an SPV file has to do a lot of work to render it in a
pretty way.

> I've also heard, but cannot confirm first-hand, that when there are
> added modules in SPSS and those modules have been used to create
> oiutput, that the viewer of the SPV file must also have those modules or
> else the computing message never goes away (because the viewer doesn't
> have the correct code to replicate the analysis).  This also seems like
> extraordinarily bad thinking (or at least has extraordinarily bad
> outcomes for users).  But, again, I cannot say I've seen this first-hand
> nor do I know if that applies to all modules.

I bet that applies only to specialized forms of output.  All pivot
tables in an SPV file share a common format, which does not require the
viewer software to recompute anything from the original data (only to
render the table), so there would be no reason for it otherwise (unless
SPSS restricts it for business reasons, to sell more of the extra
modules).