NPAR TESTS

[John Darrington]

I've started looking at the NPAR TEST command.  It has a lot of
subcommands, most of which are unrelated (IMHO they should all be
seperate commands), so I'll probably implement them one at a time
and check them in as and when they're complete.

 1.  I'm intending to put in more effort (compared to other
commands I've implemented) to seperate the parsing of the command 
from its execution.  My idea is that the parser should produce 
some kind of abstract base class, implementations of which can then 
be executed by the "backend".  I'm hopefull that this idea, if 
successful, could then be extended for all commands.

 2. In the NPAR command, spss has /SAMPLE and /METHOD subcommands, 
which, if used, make the command do monte-carlo sampling of the 
dataset rather than iteration.  So far as I can tell, this is a 
hack, to avoid memory exhaustion.  PSPP's casefiles should entirely 
avoid this problem (unless disk space is also exhausted), so I'm 
proposing that PSPP just accepts and ignores these subcommands
... unless anyone can give me a good reason to do otherwise.

 3. I've been thinking about various optimisations which NPAR can 
make.  One significant optimisation  can only be used if 
multiple tests are asked for and if /MISSING LISTWISE INCLUDE is 
specified, which can avoid extra  sorting.    However, my guess
is that few if any users will use that particular combination, so
I'm thinking that this optimisation is probably not worth the 
effort.  Comments?

 4. Many of the output tables make a lot of use of subscripted
footnotes.  I wonder how much effort it would take to implement
such a feature, as a stop-gap measure until we get a new output 
subsystem?

 5. I'm becoming aware, that different developers, and indeed the
same developers at different times, are making inconsistent use of
style in output tables, with regards to eg: text alignment, double
vs. single lines, bold fonts, output precision etc.  Perhaps we 
need a "manual of style" to make some recommendations here.

J'


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