[LON-CAPA-admin] Scantron grading problems

Stuart Raeburn raeburn at msu.edu
Thu Apr 10 18:01:44 EDT 2008


When the raw data file was re-uploaded, it will have overwritten any  
existing file (if indeed one was written to disk during the initial  
(failed) upload attempt, if you used the same file name.  The scantron  
grading screen provides an interface to download scantron data files  
uploaded to a course - the "Download: Show List of Associated Files"  
button, so this could be used to compare the raw scantron data file  
with the original data file provided by your scoring office.

LON-CAPA does not currently provide a mechanism to "wipe out" all  
grading information for a particular problem instance in a course.   
However, regrading a sequence using scantron grading will cause new  
submissions to be recorded for each student, and the last submission  
will be the one which determines the correctness, and the points  
awarded to each student for each problem part.  A side effect of  
regrading via scantron is to increment the number of tries (i.e., the  
number of tries for each problem part would become two, which might  
seem odd for a scantron exam).

My recommendation would be to download the existing raw data scantron  
file, copy it, and then remove all except the record for one student.  
Upload this "reduced" scantron data file to the course with different  
name, and then regrade with this file (this will cause new submissions  
for just that student).  You'll then be able to compare the submission  
history for that one student, to see whether the regrading made a  
difference, particularly for problem 14 onwards.  If regrading appears  
to resolve the issue, you can then regrade for the remaining students.  
If the issue is not resolved, if you can provide me with temporary CC  
access to the course, and send me the contents of  
/home/httpd/lonTabs/scantronformat.tab on the server where scantron  
grading has occurred, I can work with you to resolve the problem.

I have recently worked on a utility to allow a course coordinator to  
compare the raw scantron data record for each student, with the  
corresponding submission record stored for that student by the  
scantron grading process (it compares the last submission data).  This  
utility will report any discrepancies found (and which students are  
affected), and is expected to appear in some form in 2.7.  Contact me  
off list if you'd like to have a pre-release version of the utility  
run for this particular exam.

Stuart Raeburn

Quoting Todd Ruskell <truskell at mines.edu>:

> Hi,
> We're having some problems running some Scantron exams with version
> 2.6.2.  At some point while uploading the scantron file the first time,
> LON-CAPA spit out a long error report (I can send it on individually if
> people are interested).  Apparently it did this without
> notification to the instructor.  Additionally, at some time during the
> initial upload, the client machine got rebooted.
> A second attempt to upload scores resulted in no apparent errors.
> However, when looking at the exam statistics, after about question #15,
> the number of responses quickly diminishes, and LON-CAPA reports no
> students out of 493 got the last question (#22) correct.  In looking at
> the raw scantron file, the statistics on these last problems are not
> correct.
> So the question:  It appears that something probably has gotten
> corrupted, but what?  Is it possible to relatively easily wipe out all
> grading information for this exam and start over?  In the exam all
> problems have 5 responses except #14 and #15, which have only 4
> responses.  But we've done that kind of thing before, with no problems.
> I should also point out that an exam in a different course was graded
> with no apparent problems the same day.
> Help!
> Thanks in advance,
> Todd
> --
> Dr. Todd Ruskell
> Senior Lecturer, Department of Physics       Office:  Meyer Hall 326
> Colorado School of Mines                     Phone: 303-384-2080
> 1523 Illinois Street                         Fax: 303-273-3919
> Golden, CO 80401
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