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Differences Between: [Versions 310 and 403] [Versions 311 and 403] [Versions 39 and 403] [Versions 400 and 403]
Question statistics calculator class. Used in the quiz statistics report but also available for use elsewhere.
| Author: | Jamie Pratt <me@jamiep.org> |
| Copyright: | 2013 Open University |
| License: | http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later |
| File Size: | 494 lines (22 kb) |
| Included or required: | 0 times |
| Referenced: | 0 times |
| Includes or requires: | 0 files |
Defines 1 class
calculator:: (11 methods):
__construct()
calculate()
get_sum_of_mark_variance()
get_latest_steps()
initial_steps_walker()
initial_question_walker()
secondary_steps_walker()
secondary_question_walker()
get_random_guess_score()
get_last_calculated_time()
get_cached()
Class: calculator - X-Ref
This class has methods to compute the question statistics from the raw data.| __construct($questions, $progress = null) X-Ref |
| Constructor. param: object[] questions to analyze, keyed by slot, also analyses sub questions for random questions. param: \core\progress\base|null $progress the element to send progress messages to, default is {@link \core\progress\none}. |
| calculate($qubaids) X-Ref |
| Calculate the stats. param: \qubaid_condition $qubaids Which question usages to calculate the stats for? return: all_calculated_for_qubaid_condition The calculated stats. |
| get_sum_of_mark_variance() X-Ref |
| Used when computing Coefficient of Internal Consistency by quiz statistics. return: float |
| get_latest_steps($qubaids) X-Ref |
| Get the latest step data from the db, from which we will calculate stats. param: \qubaid_condition $qubaids Which question usages to get the latest steps for? return: array with two items |
| initial_steps_walker($step, $stats, $summarks, $positionstat = true, $dovariantalso = true) X-Ref |
| Calculating the stats is a four step process. We loop through all 'last step' data first. Update $stats->totalmarks, $stats->markarray, $stats->totalothermarks and $stats->othermarksarray to include another state. param: object $step the state to add to the statistics. param: calculated $stats the question statistics we are accumulating. param: array $summarks of the sum of marks for each question usage, indexed by question usage id param: bool $positionstat whether this is a statistic of position of question. param: bool $dovariantalso do we also want to do the same calculations for this variant? |
| initial_question_walker($stats) X-Ref |
| Then loop through all questions for the first time. Perform some computations on the per-question statistics calculations after we have been through all the step data. param: calculated $stats question stats to update. |
| secondary_steps_walker($step, $stats, $summarks) X-Ref |
| Loop through all last step data again. Now we know the averages, accumulate the date needed to compute the higher moments of the question scores. param: object $step the state to add to the statistics. param: calculated $stats the question statistics we are accumulating. param: float[] $summarks of the sum of marks for each question usage, indexed by question usage id |
| secondary_question_walker($stats) X-Ref |
| And finally loop through all the questions again. Perform more per-question statistics calculations. param: calculated $stats question stats to update. |
| get_random_guess_score($questiondata) X-Ref |
| Given the question data find the average grade that random guesses would get. param: object $questiondata the full question object. return: float the random guess score for this question. |
| get_last_calculated_time($qubaids) X-Ref |
| Find time of non-expired statistics in the database. param: \qubaid_condition $qubaids Which question usages to look for? return: int|bool Time of cached record that matches this qubaid_condition or false is non found. |
| get_cached($qubaids) X-Ref |
| Load cached statistics from the database. param: \qubaid_condition $qubaids Which question usages to load the cached stats for? return: all_calculated_for_qubaid_condition The cached stats. |
