[Contrib: Evaluation System] Sakai Evaluation system - how do you make sense of 'mean' in Evaluation results?

[Will Humphries]

Hi Fawei,

You're correct, the mean is calculated as a weighted average, with the 
first scale option worth 1 point. There is no ability to assign custom 
numeric values to the options in a scale. The 'mean' can be meaningless 
or misleading, it depends on the scale used and who you ask.

We had a local requirement at Tufts that for some scales, the rightmost 
scale option a student saw should be worth 1 point instead. To 
accomplish this, we added a check to the 'Create/Modify Scale' page 
that, when selected, reverses the order that scales options are 
displayed in when an evaluation is being taken. The work is here 
https://jira.sakaiproject.org/browse/EVALSYS-1387 , I don't think it's 
made it into community trunk.

-Will

On 2/18/14 12:25 PM, Fawei Geng wrote:
>
> Dear all,
>
> When looking at the evaluation results via the web interface, each 
> (rating scale and multiple answer ) question has a ‘mean’. Having had 
> a close look, statistically the ‘mean’ seems a bit meaningless, or 
> even misleading.
>
> For example I tested a ‘rating scale’ question. One question uses 
> 5-point ‘Strongly agree to strongly disagree’ while the other uses 
> 5-point ‘strongly disagree to strongly agree’. For both question I 
> chose the same answer –strongly agree. But I got mean =1.0 for the 
> first question and mean = 5.00 for the second question. This means 
> that the system gives the first answer a value of ‘1’ and the fifth 
> answer a value of ‘5’ regardless.
>
> Does anyone have a better way of using the ‘mean’ that I am not aware of?
>
> Many thanks
>
> Fawei
>
> ------------------------------------------------------------
> Fawei Geng, FHEA CMALT MBCS
>
> Learning Technology Support Officer
> IT Services, University of Oxford
>
> 13 Banbury Road, Oxford OX2 6NN
>
> Blog: http://blogs.oucs.ox.ac.uk/fawei/
>
> Twitter: http://twitter.com/oxford4learning/
>
> ------------------------------------------------------------
>
>
>
> _______________________________________________
> evaluation mailing list
> evaluation at collab.sakaiproject.org
> http://collab.sakaiproject.org/mailman/listinfo/evaluation
>
> TO UNSUBSCRIBE: send email to evaluation-unsubscribe at collab.sakaiproject.org with a subject of "unsubscribe"