View item statistics

Item statistics in the Gradebook are data on how your students performed on all pieces of content within a specific activity.

This information can help you to perfect the design of your content and to understand where in your content your students are excelling or struggling.

TIP: Check out Access Google Analytics for additional insights into how your students are consuming your content.

After performing a Gradebook search (check out Search for class grades), you can view this statistical data while viewing activity Gradebook data (check out View activity Gradebook data).

The item statistics are displayed in table form.

NOTE: In order for item statistics to be calculated, the content must be accessible to a student by being contained within a visible activity.

TIP: You can view item statistics for individual pieces of content across all activities that the content is used in through the Content Summary pane of the Content Repository. Check out View the Content Summary pane.

IMPORTANT: Item statistics—when viewed using the Gradebook—can differ from the statistics calculated in the Content Summary pane within the Content Repository. This is because the Gradebook captures all attempts at the piece of content within a specific activity, whereas the Content Repository captures all attempts at the piece of content across all activities that it's contained in (the latter may not differentiate between student levels of mastery). Example — If a question about a newly-learned concept is first attempted on an introductory assignment, the students viewing this question may find it more difficult and perform less optimally than when it is presented on a subsequent review assignment. Therefore, the statistics displayed in the Content Repository's Content Summary pane will be less specific to the student level of mastery completing the activity than when they are viewed using the Gradebook's Item Statistics page.

View item statistics

To view the item statistics for all of the content in a specific activity:

  1. Click Gradebook on the Class Homepage.

The Gradebook menu is the fourth menu option of the main Möbius navigational menu on the Class Homepage.

  1. Click Item Statistics.

The item statistics menu option is the second option of the Gradebook menu.

  1. Select the unit where the activity of interest is stored from the Units list.

A unit is selcted from the units list of the gradebook search page.

TIP: Select All Lessons & Assignments to display all of your class's activities in the list of available activities.

All units are selcted from the units list of the gradebook search page.

TIP: You can select more than one unit by pressing Ctrl (Mac Command) and clicking on the units you want to include in your search.

  1. Select the specific activity of interest from the list of available activities.

An activity is selcted from the activities list of the gradebook search page.

TIP: You can select more than one activity by pressing Ctrl (Mac Command) and clicking on the activities you want to include in your search.

  1. Select which class you want to use to view the item statistics from the Classes list in the Filter Results pane

A class is selcted from the classes list of the gradebook search page.

TIP: The parent class and all associated child classes will appear in the Classes list. You can select more than one class for viewing item statistics. Press Ctrl (Mac Command) and continue to select other classes to select more than one class or child class.

Multiple classes are selcted from the classes list of the gradebook search page.

Alternatively, you can:

  • Click All to select all of the classes in the Classes list.

All classes are selected using the all button below the classes list.

  • Click Default to only select the parent class in the Classes list.

Only the parent class is selected using the default button below the classes list.

  • Click Clear Selection to deselect all classes in the Classes list.

All class selection are undone using the clear selection button below the classes list.

  1. (Optional) Customize the data fields beyond the default settings that control what information is included in the calculations of your item statistics. Check out Use additional Gradebook search criteria.

List, results, progress, user, and date fields are all below the classes list.

  1. Click Search.

The search button is below all of the search fields.

  1. The item statistics are displayed as a part of the activity's/activities' Gradebook data (check out View activity Gradebook data for more details on other information that's displayed on this page).

Item statistics are displayed in table form for each question and statistical value.

TIP: Click on the preview iconThe preview quesiton icon is a blue maginifying glass.to be reminded of the question content.

The preview icon is in each description field of the item statistics table.

Click Close in the question preview to return to the item statistics.

The close button is the third button in the question preview modal.

NOTE: If you edited the activity after students have started their attempts, this can affect the accuracy of the item statistics results and you should interpret the results with caution. This interference is indicated with the caution iconThe caution icon is a yellow triangle with a black exclamation point..

The caution icon will be displayed above the item statistics table beside the activity name.

NOTE: If your activity includes a question group, questions within the question group are displayed under a single question number (Example(4)). Each question within the question group is then numbered (Example1, 2, and 3 within the question group identified as question (4)).

A quesiton group is shown in the item statistics results table.

Item statistic calculations

The numerical values of the item statistics are calculated using these formulas:

TIP: Click each statistic heading in the results table for a pop-up that explains how the value was calculated.

The heading of each item statistic in the table is clickable.

Close the explanatory pop-up window to return to the item statistics.

An X is shown in the item statistic explanation modal.

Statistic

Explanation

Success Rate

The average normalized score on the item.

With each item graded between 0.0 and 1.0 (normalized), the average score is computed over the set of all scores recorded for that item.

p-Value

The ratio of the number of fully correct responses to the total number of responses in the data set.

A question is deemed to be fully correct only if it has a score of 1.0/1.0.

  • p = F/n
  • F = number of fully correct responses
  • n = number of responses
d-Value

The discrimination of an item.

The dataset of scores is divided into two groups: those in the top-scoring half of the set and those on the bottom-scoring half.

The p-Value for each group is calculated.

The d-Value is the difference of the p-Value between the two groups.

  • d = (F1/n1) - (F2/n2)
  • F1 = number of fully correct responses from n1
  • F2 = number of fully correct responses from n2
  • n1 = number of activities with scores >= median grade for the activity
  • n2 = number of activities with scores < median grade for the activity
p-Biserial

A correlation coefficient relating the performance on an item and performance on the total activity.

An index of discrimination that measures the extent to which students who score high on the activity tend to get the item correct and those who score low tend to get the item incorrect.

  • r sub pb equals left parenthesis Y subs 1 minus Y sub 0 right parenthesis times square root of p times q end root divided by sigma sub Y.
  • Y1 = mean grade of activities on which this item was answered correctly (1.0).
  • Y0 = mean grade of activities on which this item was answered incorrectly.
  • p = p-Value
  • q = 1-p
  • sigma sub Y= standard deviation for activity grades.
r-Biserial

A correlation coefficient relating performance on an item and performance on the total activity.

An index of discrimination that measures the extent to which students who score high on the activity tend to get the item correct and those who score low tend to get the item incorrect.

  • r sub b equals left parenthesis Y sub 1 minus Y sub 0 right parenthesis times left parenthesis p times q over Y right parenthesis divided by sigma sub Y.
  • Y1 = mean grade of activities on which this item was answered correctly (1.0).
  • Y0 = mean grade of activities on which this item was answered incorrectly.
  • p = p-Value
  • q = 1-p
  • Y = the height of the standardized normal distribution at the point z, where P(z'<z)=q and P(z'>z)=p.
  • sigma sub Y= standard deviation for activity grades.
Count The number of times students have attempted this question.
Correct The number of times a student has answered this question and received a score of 1.0/1.0.
Partial The number of times a student has received a partial mark (0.0 < x < 1.0/1.0) for this question.
Incorrect The number of times a student has received a score of 0.0/1.0 for this question.