Quiz Access Rule quizaccess_delayed

Auto Activate the Quiz Attempt Button with a randomized delay to reduce the load at the start of the quizes.

Background and Need

Mitigating Student Avalanches at the Start of a Quiz

Overload of servers

In a quiz with strict time constraints students tend to refresh the page too often, just to make sure if the attempt is available yet.
This unnecessarily increases the server load, and is a problem with large number of students.
Synchronized start of many attempts places a heavy short-time load in the Quiz core engine. By phasing in access, the impact is minimized.

Advises on the configuration of the questionnaire

Some quiz configurations generate particularly high server loads.
Some quiz schedules generate problems for the students.

Solution

Control the access of students in a transparent and friendly way

Flattening the curve

By having the students enter gradually the load curve is flattened and the system can handle many more users doing tests.

Waiting room with a countdown

The “Delayed Attempt” plugin makes the “Attempt quiz now” button auto-enable at quiz open timing plus a randomized delay, without requiring to refresh the page.
This is done by a client side countdown timer (javascript) which is initiated when the page is rendered in the browser. The page, displays the time remaining to start the quiz using an animated countdown.

Fully customizable

The plugin is implemented as an access-rule plugin overriding the default activity page render.
A pseudo-random delay is assigned to each student depending on the number of students and a set of site-wide parameters as fixed rate of entry, maximum allowable delay.
An optional message for the students can be defined for all quizzes in the platform.
An optional check and advice message for teachers can be defined for all quizzes in the platform.

How the delay is calculated

The plugin acts only until the instant of the start of the quiz plus the number of minutes of maximum delay. After that it doesn't work anymore because the critical moment of the start is supposed to be over. The maximum delay is calculated as follows:

Number of students divided by the entry rate specified by the administrator. E.g. with 25 students/minute, if the course has 200 students, the maximum delay will be 8 minutes.
Maximum of 10% of the test duration. We have considered that it is not logical to wait 4 minutes for a 15-minute exam. E.g. 15 minute exam => maximum wait of 1.5 minutes.
Maximum time limit defined by the administrator. This is to put a reasonable limit in the case of large groups at the cost of suffering a higher entry fee. E.g. maximum 4 minutes.
At least 1 minute. This is to ensure that there is always gradual access. With 1 minute, students do not notice the delay because it is in the range of accuracy of the usual clock.

With all these limitations, the final entry rate is the one needed to meet all specifications. In this example it would be 200 students/1.5 minutes = 133 students/minute (about 2 per second). If we want to spit out the input rate we will have to give up the absolute limit or the percentage of the completion time. In the UVa we have decided that a long delay is not functionally admissible in the case of short exams, because it would make some students almost finish and others would still be starting.

How a quiz is marked as "resource-intensive" or "problematic"

In our experience, a mass quiz is "resource-intensive" aka "problematic" when it meets these characteristics:
- It's paged so that each page will last less than 10 minutes.
- The time allotted is too tight.
- The entry rate of students is too high.

The time alloted is considered too tight if :
- The total time allotted is less than:
- the completion time plus the gradual entry delay plus 10% of the completion time. (An opening of the activity of less than this time does not allow to face the small incidences of any test.)
- not excess 20% of the execution time.

Address

E.T.S.I. Telecomunicación
Univesidad de Valladolid
Paseo de Belén 13
Valladolid, 47011
Spain

Contact

Email: jpdecastro@tel.uva.es

Links

E.T.S.I.T.
Install from Repository

Feedback

Please send us your ideas, bug reports, suggestions! Any feedback would be appreciated.

Mobirise website maker - More info