What Is PBCC (Point-Biserial Correlation Coefficient)?

This article explains the PBCC (Point-Biserial Correlation Coefficient).

This Guide is for:

  • Super Admin
  • Teacher Admin (Full-Access)
  • Teacher (Owner Full-Access)

Using the statistical information provided on your dashboard to review your test can provide useful information.

On the Item Analysis table of the your IRAT Dashboard, the heading of the last column reads PBCC.


PBCC, also referred to as the Point-Biserial Correlation Coefficient shows the relationship between how the student performs on the item and their total test score.
  • The range is from –1.00 to 1.00.
  • The higher the value, the more discriminating the item. This indicates that students who got high test scores got the item correct, whereas students who had low test scores got the item incorrect.
  • Items with discrimination values near or less than 0 should be removed from the test. This indicates that students who did poorly overall did better on that item than students who did well overall. 
  • The acceptable range: 0.20 or higher
  • The ideal value: Closer to 1.00.




pbcc3    The mean total score for persons who have responded correctly to the item
pbcc4    The mean total score for all persons
pbcc5      The difficulty value for the item
pbcc6      p-1
pbcc7    The standard deviation of total test scores

How does InteDashboard calculate the PBCC of the Point-spreading type of IRAT?

InteDashboard treats partials scores as zero. This means that if a student in a confidence-based test gets 50% points in the question, we treat it as wrong because they are not 100% correct.


Still need help?  Reach out to us at support@intedashboard.com or book a call with one of our customer advisors here.