[LON-CAPA-users] entering the same answer twice

[Stuart Raeburn]

Hi Doug,

> I might be mistaken but I *thought* in the past I'd seen Lon-Capa   
> recognize different ways of expressing the same value as "you've   
> entered that answer before" and not counting the attempt in   
> numericalresponse problems.

Submitting (incorrect) answers of 0.650 and 0.65 for a  
numericalresponse item results in tries being charged for both  
submissions in LON-CAPA versions 2.9, 2.10, and 2.11.

Checking if the same answer was submitted for a numericalresponse item  
is determined in the end_numericalresponse() routine in  
/home/httpd/lib/perl/Apache/caparesponse.pm, which in turn calls the  
check_for_previous() routine in /home/httpd/lib/perl/Apache/response.pm

The check involves a string comparison of the current submission with  
each of the previous submissions made by the student for the same  
instance of the response item.

If there is an exact match between the value of the current submission  
and the value of a past submission, (and the awards also matched),  
then the message: 'You have entered that answer before' will be shown  
and no try will be charged.
(Exception: survey items, or items where the random seed has changed,  
i.e., randomizetry parameter in effect).

That string comparison part of the implementation has not changed from  
response.pm rev. 1.32 (8/3/2001) and caparesponse.pm rev. 1.38  
(8/3/2001).


Stuart Raeburn
LON-CAPA Academic Consortium

Quoting "Mills, Douglas G" <dmills at illinois.edu>:

> Hi All,
>
> I might be mistaken but I *thought* in the past I'd seen Lon-Capa   
> recognize different ways of expressing the same value as "you've   
> entered that answer before" and not counting the attempt in   
> numericalresponse problems. Am I wrong about that?  I thought   
> entries such as .650 and 0.650 were recognized as the same answer   
> and the second entry then not counted as a try where there a limited  
>  number of tries, but if that had been the case in the past, it does  
>  not seem to be the case now.  A student reported using her two  
> tries  on a test retake with just those two answers (why, I don't  
> know!)  and my subsequent testing of that and some other items  
> confirmed  that attempts are not counted by values but by different  
> expressions  of those values -- as if the problem were a  
> stringresponse.  That  was not what I expected.  Thank you for any  
> further guidance on  that. Could it be related to changes addressing  
> differences between  decimals with trailing zeros (so .650 is not  
> the same as .65 for  purposes of sig figs) or something?  Or was I  
> imagining that those  different expressions were recognized as the  
> same value in the past?
>
> Doug
>
> Douglas Mills
> Director of Instructional Technologies
> Department of Chemistry
> University of Illinois
> dmills at illinois.edu<mailto:dmills at illinois.edu>
> (217) 244-5739