core_question\statistics\questions\calculated_question_summary Class Reference

Class calculated_question_summary. More...

Inheritance diagram for core_question\statistics\questions\calculated_question_summary:

Public Member Functions
	__construct ($question, $slot, $subqstats)
	calculated_question_summary constructor.
	break_down_by_variant ()
	This is a summary stat so never breakdown by variant.
	cache ($qubaids, $timemodified=null)
	Cache calculated stats stored in this object in 'question_statistics' table.
	clear_variants ()
	Delete the data structure for storing variant stats.
	get_min_max_of ($attribute)
	Returns the minimum and maximum values of the given attribute in the summarised calculated stats.
	get_sub_question_ids ()
	Get any sub question ids for this question.
	get_variants ()
	Array of variants that have appeared in the attempt data for this question.
	populate_from_record ($record)
	Load properties of this class from db record.
	random_selector_string ()
	Used to determine which random questions pull sub questions from the same pools.
	sort_variants ()
	Sort the variants of this question by variant number.

Public Attributes
	$covariance
	$covariancemax
	$covariancemaxsum = 0
	$covariancesum = 0
	$covariancewithoverallmark
	$covariancewithoverallmarksum = 0
float	$discriminationindex
float	$discriminativeefficiency
float	$effectiveweight
	effective weight of this question.
float	$facility
	$markarray = array()
	$markaverage
	$markvariance
	$markvariancesum = 0
float	$maxmark
	max mark achievable for this question.
string	$minmedianmaxnotice = ''
	if this stat has been picked as a min, median or maximum facility value then this string says which stat this is.
bool	$negcovar
	is covariance of this questions mark with other question marks negative?
	$othermarkaverage
	$othermarksarray = array()
	$othermarkvariance
	$othermarkvariancesum = 0
string	$positions
	comma separated list of the positions in which this question appears.
object	$question
	full question data
	$questionid
null float	$randomguessscore = null
	The average score that students would have got by guessing randomly.
int	$s = 0
	total attempts at this question.
float	$sd
	standard deviation
	$slot = null
int	$subqdisplayorder
	only set immediately before display in the table.
bool	$subquestion = false
	is this a sub question.
	$subquestions = ''
float	$summarksaverage
	The average for all attempts, of the sum of the marks for all positions in which this item appeared.
integer	$timemodified
	Set if this record has been retrieved from cache.
	$totalmarks = 0
	$totalothermarks = 0
float	$totalsummarks = 0
	The total of marks achieved for all positions in all attempts where this item was seen.
null integer	$variant = null
	if this property is not null then this is the stats for a variant of a question or when inherited by calculated_for_subquestion and not null then this is the stats for a variant of a sub question.
calculated[]	$variantstats = array()
	An array of calculated stats for each variant of the question.

Protected Member Functions
	get_min_max_of_sd ()
	Returns the minimum and maximum values of the standard deviation in the summarised calculated stats.
	max (float $value1=null, float $value2=null)
	Find higher value.
	min (float $value1=null, float $value2=null)
	Find lower value.

Protected Attributes
	$fieldsindb
calculated[]	$subqstats
	The instances storing the calculated stats of the questions that are being summarised.

Detailed Description

Class calculated_question_summary.

This class is used to indicate the statistics for a random question slot should be rendered with a link to a summary of the displayed questions.

It's used in the limited view of the statistics calculation in lieu of adding the stats for each subquestion individually.

Copyright

2018 Ryan Wyllie ryan@.nosp@m.mood.nosp@m.le.co.nosp@m.m

License

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

Constructor & Destructor Documentation

__construct()

core_question\statistics\questions\calculated_question_summary::__construct	(		$question,
			$slot,
			$subqstats )

calculated_question_summary constructor.

Parameters

stdClass	$question
int	$slot
calculated[]	$subqstats	The instances of the calculated stats of the questions that are being summarised.

Reimplemented from core_question\statistics\questions\calculated.

Member Function Documentation

break_down_by_variant()

core_question\statistics\questions\calculated_question_summary::break_down_by_variant

(

)

This is a summary stat so never breakdown by variant.

Return values

bool

Reimplemented from core_question\statistics\questions\calculated.

cache()

core_question\statistics\questions\calculated::cache ( $qubaids, $timemodified = null )

inherited

Cache calculated stats stored in this object in 'question_statistics' table.

Parameters

qubaid_condition	$qubaids
int | null	$timemodified	the modified time to store. Defaults to the current time.

get_min_max_of()

core_question\statistics\questions\calculated_question_summary::get_min_max_of

(

$attribute

)

Returns the minimum and maximum values of the given attribute in the summarised calculated stats.

Parameters

string

$attribute

The attribute that we are looking for its extremums.

Return values

array

An array of [min,max]

get_min_max_of_sd()

core_question\statistics\questions\calculated_question_summary::get_min_max_of_sd ( )

protected

Returns the minimum and maximum values of the standard deviation in the summarised calculated stats.

Return values

array

An array of [min,max]

get_sub_question_ids()

core_question\statistics\questions\calculated::get_sub_question_ids ( )

inherited

Get any sub question ids for this question.

Return values

int[]

array of sub-question ids or empty array if there are none.

get_variants()

core_question\statistics\questions\calculated::get_variants ( )

inherited

Array of variants that have appeared in the attempt data for this question.

Or an empty array if there is only one variant.

Return values

int[]

the variant nos.

max()

core_question\statistics\questions\calculated_question_summary::max ( float $value1 = null, float $value2 = null )

protected

Find higher value.

A zero value is almost considered equal to zero in comparisons. The only difference is that when being compared to zero, zero is higher than null.

Parameters

float | null	$value1
float | null	$value2

Return values

float|null

min()

core_question\statistics\questions\calculated_question_summary::min ( float $value1 = null, float $value2 = null )

protected

Find lower value.

A zero value is almost considered equal to zero in comparisons. The only difference is that when being compared to zero, zero is lower than null.

Parameters

float | null	$value1
float | null	$value2

Return values

mixed|null

populate_from_record()

core_question\statistics\questions\calculated::populate_from_record ( $record )

inherited

Load properties of this class from db record.

Parameters

object

$record

Given a record from 'question_statistics' copy stats from record to properties.

random_selector_string()

core_question\statistics\questions\calculated::random_selector_string ( )

inherited

Used to determine which random questions pull sub questions from the same pools.

Where pool means category and possibly all the sub categories of that category.

Return values

null|string

represents the pool of questions from which this question draws if it is random, or null if not.

Member Data Documentation

$fieldsindb

core_question\statistics\questions\calculated::$fieldsindb

protectedinherited

Initial value:

= array('questionid', 'slot', 'subquestion', 's', 'effectiveweight', 'negcovar', 'discriminationindex',
        'discriminativeefficiency', 'sd', 'facility', 'subquestions', 'maxmark', 'positions', 'randomguessscore', 'variant')

$minmedianmaxnotice

string core_question\statistics\questions\calculated::$minmedianmaxnotice = ''

inherited

if this stat has been picked as a min, median or maximum facility value then this string says which stat this is.

Prepended to question name for display.

$randomguessscore

null float core_question\statistics\questions\calculated::$randomguessscore = null

inherited

The average score that students would have got by guessing randomly.

Or null if not calculable.

$subqdisplayorder

int core_question\statistics\questions\calculated_question_summary::$subqdisplayorder

only set immediately before display in the table.

The order of display in the table.

$timemodified

integer core_question\statistics\questions\calculated::$timemodified

inherited

Set if this record has been retrieved from cache.

This is the time that the statistics were calculated.

$variantstats

calculated [] core_question\statistics\questions\calculated::$variantstats = array()

inherited

An array of calculated stats for each variant of the question.

Even when there is just one variant we still calculate this data as there is no way to know if there are variants before we have finished going through the attempt data one time.

$variants

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

• question/classes/statistics/questions/calculated_question_summary.php