Matrix Question Type Specification

Introduction

I need to develop a n:n matching type of question that is suited to a matrix. The teacher should be able to define the matrix and the various grading options.

The follow serves as my very high level (mostly technical) specification.

Some examples

Here are three simple examples of the way this question type could be used. ( ) is mean to be a radio button. [ ] is a checkbox.

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Evaluate the following statements:

	True	False
Moodle is a learning management system	(*)	( )
Mahara is an ePortfolio system	(*)	( )
Moodle has no bugs	( )	(*)
This proposal is a good idea	(*)	( )

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Which colours are mixed on your computer's monitor to make each of the listed colours:

	Red	Green	Blue
Red	[*]	[ ]	[ ]
Magenta	[*]	[ ]	[*]
Cyan	[ ]	[*]	[*]
Black	[ ]	[ ]	[ ]
White	[*]	[*]	[*]

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Match the adult to their young:

	Tadpole	Joey	Foal	Puppy
Poney	( )	( )	(*)	( )
Frog	(*)	( )	( )	( )
Kangaroo	( )	(*)	( )	( )

But the most useful example is probably the Likert Scale:

How often do you do the following?

	Never	Very rarely	Rarely	Occasionally	Frequently	Very Frequently
Brush your teeth	[]	[ ]	[ ]	[*]	[ ]	[]
Cook your own dinner	[*]	[ ]	[]	[]	[ ]	[]
Make your bed	[ ]	[]	[]	[]	[ ]	[*]
Dye your hair	[ ]	[ ]	[ ]	[*]	[ ]	[]
Pick your nose	[]	[]	[*]	[]	[ ]	[]

Database Tables

Question Definition Tables

question_matrix

Contains basic information about the matrix - what the grading method and whether multiple checks per row are supported(eg checkboxes vs radio buttons) The grading methods translate to:

• ALL - the student must select ALL correct answers and get 100%, else 0%.
• ANY - the student must select at least one of the correct answers, and get 100% else 0%.
• WEIGHTED - each cell has a weighting from -100% to 100%. The "correct" answers must add up to 100%, but the 0 and negative ones don't have any constraint on them.
• NONE - this could be used for example for Likert scales.
• SUM of CORRECT ANSWERS - each row is graded. The user is able to choose the percentage on basis of the number of correct answers in all rows. For the first example (4 true/false-questions about moodle) the student selects 4 correct answers in 4 rows --> 100%. The student selects 3 correct answers out of 4 rows (it does not matter if the student has checked the wrong button or hasn't checked any button in the fourth row) --> 50%. The student selects 2, 1 or 0 correct answers out of 4 rows --> 0% (because one can obtain 2 correct answers out of 4 rows by guessing. The probability of a correct answer is 50% in each row).

field	notes
id	sequence
questionid	fk to mdl_question
multiple	boolean
grading	(ALL or ANY of WEIGHTED or NONE) enum or fk to another table containing these values.
roundzero	If the total for the question is less than 0, set it to 0. (This can be triggered by highly negative weights)
renderer	'matrix' hardcoded at the moment (see implementation notes)

question_matrix_cols

Contains the definition of the matrix columns

field	notes
id	sequence
matrixid	fk to question_matrix
shorttext	short word to fit in
longtext	title or hover or something

question_matrix_rows

Contains the definition of the matrix rows

field	notes
id	sequence
matrixid	fk to question_matrix
shorttext	short word to fit in
longtext	title or hover or something

question_matrix_weights

Contains more information about how each cell should be graded. EVERY cell should have an entry in this table. When the grading method is 'all' or 'any', the 'correct' answers will be stored here as a non-zero percentage automatically and the non-correct answers will be zero.

field	notes
id	sequence
rowid	fk to question_matrix_rows
colid	fk to question_matrix_cols
weight	percentage value

Student Answer Tables

question_matrix_answers

This table contains a list of all the cells that the student has selected.

field	notes
id	sequence
rowid	fk to question_matrix_rows
colid	fk to question_matrix_cols

Implementation notes

Grading

There should be classes to match the grading types (all or any or weighted) so that new options could be written.

Renderers

It may make sense for some point for some different method to be used to render this to the user, so we can start with a matrix class and maybe add more later if necessary.

Penny's TODO

• Find out about roundzero
• Find out about constant namespacing in qtypes.