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Re: Algorithm Question Again

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Mon, 15 Nov 2010 18:20:20 +0000

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 ```Hi Simon I am one of the people responsible for designing the algorithm. From my perspective it is easy to justify the higher weightings and higher marks in your scenario, this is how the system is meant to work and not a quirk in the system. If both groups scored an overall average of 74, but in one group they all performed equally then they should have the same mark, however in group B one student did much less work, yet they performed equally well. So it then follows that there was more work for the rest of the team and someone else had to put in more work to compensate, so it is valid that one team member received a higher score. I think your question is more about mark distribution, which also depends on your own marking criteria and assessment independent of WebPA. You can change the distribution of the marks by altering the peer assessed weighting. Peter Willmot and I provide a rationale for having a weighting in this paper: https://dspace.lboro.ac.uk/dspace-jspui/bitstream/2134/6490/1/Willmott-Crawford-2007.pdf This is based upon using 50% weighting for peer assessment which shows a good match to Steven Hansonâ€™s data (55%). We also found that the extremes were representative of the student effort and achievement by validating marks through 4th year mentors. Following your second e-mail. All the scores are normalised so if there are 4 students in the group each will allocate 1/4 of the marks, for 5 students in the group each will allocate 1/5 of the marks etc. The more people in the group who are not pulling their weight the more work will be required by the key person and the higher their weighting could become, which is intentionally how the algorithm is designed. Best regards Adam ________________ Dr Adam Crawford engCETL Manager Loughborough University www.engcetl.ac.uk -----Original Message----- From: WebPA Project [mailto:[log in to unmask]] On Behalf Of Simon Brookes Sent: 15 November 2010 14:28 To: [log in to unmask] Subject: Algorithm Question Again There is another problem with the WebPA algorithm (I think!). According to the "worked example of the scoring algorithm" in WebPA Help, the final individual WebPA score a student gets is a function of the number of students in the group - the combined fractions awarded by each student for each individual. So, the more students within each group, the higher the scores will be! This problem is most exaggerated in a scenario where one student performs very poorly compared with the rest of the group or vice versa - a common occurrence in my experience. See my worked example showing the difference in final marks for groups of students with 5 and 4 members respectively. The group marks were the same (74) but look at the effect on the final mark. https://spreadsheets.google.com/pub?key=0AlaZW47BQdRVdHZCY0FoOGNRUXNTR1dGdUswR2lrZGc&single=true&gid=3&output=html Do the designers of the algorithm have any comments? Cheers Simon >>> Neil A Gordon <[log in to unmask]> 11/11/2010 16:37 >>> Hi Simon I share your reservations - and usually end up moderating such cases, and similarly when the algorithm ends up allocating a mark of 100% to individual members of a team. Some colleagues use the option to alter the proportion of how much is allocated by the algorithm, e.g. 50% from the original mark, 50% through webpa - although in my view that introduces another artificial allocation (so within a team, a student who was allocated zero by the algorithm would still get 50% of the overall team mark). It seems to me that tutor moderation is the safest bet rather than relying fully on the output from the algorithm. A cap on the top mark could be one solution - although I'm not aware of that functionality at the moment - beyond using the proportion option to restrict the available variability. What do others think? Neil -----Original Message----- From: WebPA Project [mailto:[log in to unmask]] On Behalf Of Simon Brookes Sent: 11 November 2010 16:04 To: [log in to unmask] Subject: Algorithm Question Hi I have been playing around with the WebPA algorithm in a spreadsheet this afternoon. I would welcome some thoughts/advice please. You can see the example here: https://spreadsheets.google.com/pub?key=0AlaZW47BQdRVdDlTWHpMU3JXNDRMMEh Yb3lsaWE5b1E&hl=en_GB&single=true&gid=3&output=html I completely understand how the current algorithm works - this is not my issue. The problem I have is illustrated if you compare the marks for Groups A and B. 1. You'll see that both groups received the same group mark (74%) 2. The individual marks are modified by the peer assessment. 3. However, I am really unhappy that one student in Group B ends up with a mark of 97% while the top mark in Group A ends up as 82%. 4. Overall I deemed that the appropriate mark for both presentations was 74% but the calculation ends up awarding one student in one group (which received exactly the same group as the other) a much higher final mark. 5. To me, this does not seem fair. Group B's work was not any better than Group A but, because of a quirk of the system (actually because one student performed particularly poorly in Group B), these students mostly end up with much higher marks. I have always felt uncomfortable about this when using this type of algorithm in the past. The individual mark distribution works fine within groups but not when one compared between groups. Would there be a way of say capping the top mark at that given as the group mark then all other marks distributed relative to that? Thanks Simon ```