Re: [WWdevel] webwork: problem values getting set to zero

[P G. L. <gl...@um...>]

Hi John,

I think
     * in all cases, when storing "" in the database, store it as NULL.
       It will be promoted back when the information is retrieved.  I
       think this is safe.
is the easiest fix.  Aesthetically I like the idea of calling something
that has integer values an integer when defining the database, so from a
purely artistic viewpoint I'd vote against
     * stop using integer types in the database.

Gavin

On Thu, 14 Jul 2005 at 11:03 John Jones wrote:

> This discussion of storing the student's score refers to the
> student-problem field status.  It was not affected by my changes to the
> types of fields in mysql databases - it is still stored as type text
> rather than type int.  (Maybe it should be stored as an int, but that's
> a different question.)
>
> The problem Gavin discovered was with value - the number of points the
> problem is worth.  It is one of several fields currently stored as type
> int, and they probably all will suffer the same difficulty if they are
> override fields for a more global value.  It is a pretty serious bug, so
> I will attempt to fix this as soon as we know which way we want to go.
>
> I think our options are:
>     * in all cases, when storing "" in the database, store it as NULL.
>       It will be promoted back when the information is retrieved.  I
>       think this is safe.
>     * when storing back to the database, only demote "" to NULL if the
>       field is of integer type.
>     * stop using integer types in the database.
>
>
> John
>
>
> Michael Gage wrote:
>
> >
> > On Jul 14, 2005, at 12:45 PM, P Gavin LaRose wrote:
> >
> >>
> >> Isn't the distinction between "haven't tried" and "score of zero" also
> >> captured by the attempted field in problem_user?  I think if the status
> >> codes this also, it's redundant information.
> >>
> >> Am I making sense?
> >> Gavin
> >>
> > That makes sense to me.  I believe that we tried to eliminate all of
> > the null responses
> > when extracting scoring data because we were getting a lot spurious
> > "undefined variables" warnings.  We also get a  lot of "non-numeric in
> > comparison" errors
> > when sorting, etc. etc. etc.  In any case I think this is why most
> > things are promoted
> > from null at least to "" or to 0.
> >
> > In light of what you have pointed out I suggest that we "insist" that
> > the student score
> > be a number.  I believe that blanks are automatically converted to 0,
> > so they would be ok in sorts.
> > (I haven't checked this.)  Otherwise we'll need checks in every sort
> > routine as well as other places.
> > Use the "attempts" field to determine if the problem hasn't been tried
> > yet.
> >
> > We may need to fix some assumptions in the grading and scoring
> > packages to conform to this.
> > The simplification in sorts that we gain by assuming that score is
> > always a number seems to
> > me to outweigh desires for more, occasionally non-numeric states.
> >
> > Take care,
> >
> > Mike
> >
> >
> >> On Thu, 14 Jul 2005 at 12:39 Michael Gage wrote:
> >>
> >>> Could we get a list of what states are needed for the student score?
> >>>
> >>> number     -- means the student has achieved this score on this problem
> >>> 0                --  means the student has tried this problem but
> >>> hasn't gotten in correct
> >>> null/ blank  -- means that the student hasn't tried the problem.
> >>>
> >>> Are there are other states we need?
> >>>
> >>> Do we need the state that distinguishes between "hasn't tried the
> >>> problem" and the one where the score is zero?
> >>> I think perhaps we do, so that we can warn the student they haven't yet
> >>> completed an assignment while not
> >>> bugging them about problems that they haven't successfully completed.
> >>>
> >>> any other thoughts on what is needed?
> >>>
> >>> Take care,
> >>> Mike
> >>
> >>
> >> --
> >> P. Gavin LaRose, Ph.D.  Program Manager (Instructional Tech.)
> >> Math Dept., University of Michigan
> >> gl...@um...                        "There's no use in trying,"
> >> [Alice]
> >> 734.764.6454                             said. "One Can't believe
> >> impossible
> >> http://www.math.lsa.umich.edu/~glarose/  things." "I daresay you
> >> haven't had
> >>                                          much practice," said the Queen.
> >>                                                               - Lewis
> >> Carrol
> >>
> >
> >
> >
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>
>
>

-- 
P. Gavin LaRose, Ph.D.  Program Manager (Instructional Tech.)
Math Dept., University of Michigan
gl...@um...                        "There's no use in trying," [Alice]
734.764.6454                             said. "One Can't believe impossible
http://www.math.lsa.umich.edu/~glarose/  things." "I daresay you haven't had
                                         much practice," said the Queen.
                                                              - Lewis Carrol