From the PARcore Data Visualization Studio Landing Page, navigate to this report by selecting the DIF Frequency Graphs report icon.   This report is only applicable for requests that include the Analysis Type of Item Analysis - Differential Item Functioning. 

The bento box menu icon at the top left of the report can be used to navigate back to the Landing Page.
 




When first launching the report it will be empty.  Make initial filter selections in order to visualize the report.  Any filter with a red asterisk indicates it is required to have a selection made before the report can be displayed.


Filters
Refer to Visualize Results for general information about filter navigation for any report.  The filters for this report are:



 

• Analysis - select one analysis sequence number to view at a time.  The analysis sequence number will reflect the sequencing from Request Details for this request.
  • Upon first initializing this dashboard, the filter will display as (Choose your analysis) and a selection must be made. 
  • Select the search icon (magnifying glass) and enter search text to see Analysis filter options for the request you are viewing.  Using an asterisk in the search text box will display all possible analyses to choose from.  
  • Once the current analysis results have been reviewed, continue to use the search feature or utilize the slider arrows (< and >) to view each analysis one at a time.  If you only have one analysis to view, the slider arrows will be disabled.
  • The filter description will include the criterion score being analyzed as well as the reference and focal group.  Only one reference/focal group comparison will be displayed at a time.

• Refinement Type - select one refinement to view at a time.  
  • Upon first initializing this dashboard, the filter will display as (Choose refinement type.) and a selection must be made before any data is visualized.  Use the dropdown filter to display the possible refinements stored for this comparison group.  
  • The available refinement type(s) to choose from depend upon the user selected options for this analysis as well as the analysis results.  The available options are:
    • No Refinement:  This will appear if the user selected "No" to the analysis template option to Refine Criterion Score.  This will be the only refinement option available.
    • None Required:  This will appear if the user selected "Yes" to the analysis template option to Refine Criterion Score but the comparison analysis resulted in no C items and therefore no refinement was performed.  This will be the only refinement option available.
    • Before Refinement:  This will be available if the user selected "Yes" to the analysis template option to Refine Criterion Score and the comparison analysis resulted in at least one C item.  The dropdown menu should show both "Before Refinement" and "After Refinement" as options.  Selecting Before Refinement will display the frequency distributions and summary statistics before refinement was performed. 
    • After Refinement:  This will be available if the user selected "Yes" to the analysis template option to Refine Criterion Score and the comparison analysis resulted in at least one C item.  The dropdown menu should show both "Before Refinement" and "After Refinement" as options.  Selecting After Refinement will display the frequency distributions and summary statistics after criterion refinement was performed.

• The "Relative Frequency Distribution Comparison" graph is displayed on the left.  
  • This graph plots the relative frequency (percent at) against the criterion score for the reference group and focal group. 
  • A tooltip appears when hovering over any plot point to display both the relative frequency value and criterion score value for that plot point. 
  • There is a legend beneath this graph to indicate that the reference group is the thinner red plot line, while the focal group is the thicker blue plot line.  This legend is relevant for both frequency plots being displayed.

• The "Cumulative Relative Frequency Distribution Comparison" graph is displayed on the right.  
  • This graph plots the cumulative relative frequency  against the criterion score for the reference group and focal group. 
  • A tooltip appears when hovering over any plot point to display both the cumulative relative frequency value and criterion score value for that plot point. 
  • The reference group is the thinner red plot line, while the focal group is the thicker blue plot line.

• If desired, utilize the zoom feature to expand either plot to get a closer look at the data points.  Refer to Visualize Results for general information about the zoom functionality for any report that contains plots.    

• Below the graphs there will be summary statistics (N, Mean, SD (N), 75th Percentile, Median, 25th Percentile) displayed for both the focal group and reference group.