question_cbm Class Reference

This helper class contains the constants and methods required for manipulating scores for certainty based marking. More...

Static Public Member Functions
static	adjust_fraction ($fraction, $certainty)
	Given a fraction, and a certainty, compute the adjusted fraction.
static	default_certainty ()
	#-
static	get_short_string ($certainty)
static	get_string ($certainty)
static	optimal_probablility_high ($certainty)
static	optimal_probablility_low ($certainty)
static	summary_with_certainty ($summary, $certainty)
	Add information about certainty to a response summary.

Public Attributes
const	HIGH = 3
integer const	LOW = 1
	#+ named constants for the certainty levels.
const	MED = 2

Static Public Attributes
static array	$certainties = array(self::LOW, self::MED, self::HIGH)
	#-

Static Protected Attributes
static	$highlimit
static array	$lowlimit
	#-
static array	$rightscore
	#+ coefficients used to adjust the fraction based on certainty.
static	$wrongscore

Detailed Description

This helper class contains the constants and methods required for manipulating scores for certainty based marking.

Copyright

2009 The Open University

License

http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

Member Function Documentation

adjust_fraction()

static question_cbm::adjust_fraction ( $fraction, $certainty )

static

Given a fraction, and a certainty, compute the adjusted fraction.

Parameters

number	$fraction	the raw fraction for this question.
int	$certainty	one of the certainty level constants.

Return values

number

the adjusted fraction taking the certainty into account.

default_certainty()

static question_cbm::default_certainty ( )

static

#-

Return values

int	the default certaintly level that should be assuemd if the student does not choose one.

get_short_string()

static question_cbm::get_short_string ( $certainty )

static

Parameters

int

$certainty

one of the LOW/MED/HIGH constants.

Return values

string

a short textual description of this certainty.

get_string()

static question_cbm::get_string ( $certainty )

static

Parameters

int

$certainty

one of the LOW/MED/HIGH constants.

Return values

string

a textual description of this certainty.

optimal_probablility_high()

static question_cbm::optimal_probablility_high ( $certainty )

static

Parameters

int

$certainty

one of the LOW/MED/HIGH constants.

Return values

float

the upper limit of the optimal probability range for this certainty.

optimal_probablility_low()

static question_cbm::optimal_probablility_low ( $certainty )

static

Parameters

int

$certainty

one of the LOW/MED/HIGH constants.

Return values

float

the lower limit of the optimal probability range for this certainty.

summary_with_certainty()

static question_cbm::summary_with_certainty ( $summary, $certainty )

static

Add information about certainty to a response summary.

Parameters

string	$summary	the response summary.
int	$certainty	the level of certainty to add.

Return values

string

the summary with information about the certainty added.

Member Data Documentation

$certainties

array question_cbm::$certainties = array(self::LOW, self::MED, self::HIGH)

static

#-

list of all the certainty levels.

$highlimit

question_cbm::$highlimit

staticprotected

Initial value:

= array(
        self::LOW  => 0.666666666666667,
        self::MED  => 0.8,
        self::HIGH => 1,
    )

$lowlimit

array question_cbm::$lowlimit

staticprotected

Initial value:

= array(
        self::LOW  => 0,
        self::MED  => 0.666666666666667,
        self::HIGH => 0.8,
    )

#-

#+ upper and lower limits of the optimal window.

$rightscore

array question_cbm::$rightscore

staticprotected

Initial value:

= array(
        self::LOW  => 1,
        self::MED  => 2,
        self::HIGH => 3,
    )

#+ coefficients used to adjust the fraction based on certainty.

$wrongscore

question_cbm::$wrongscore

staticprotected

Initial value:

= array(
        self::LOW  =>  0,
        self::MED  => -2,
        self::HIGH => -6,
    )

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The documentation for this class was generated from the following file:

• question/behaviour/behaviourbase.php