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Norm-Referenced vs. Criterion-Referenced Testing

Norm-Referenced vs. Criterion-Referenced Testing standard

The two terms Norm-Referenced and Criterion-Referenced are commonly used to describe tests, exams, and assessments.  They are often some of the first concepts learned when studying assessment and psychometrics.

Norm-referenced means that we are referencing how your score compares to other people.  Criterion-referenced means that we are referencing how your score compares to a criterion such as a cutscore or a body of knowledge.

Do we say a test is “Norm-Referenced” vs. “Criterion-Referenced”?

Actually, that’s a slight misuse.

The terms Norm-Referenced and Criterion-Referenced refer to score interpretations.  Most tests can actually be interpreted in both ways, though they are usually designed and validated for only one of the other.

Hence the shorthand usage of saying “this is a norm-referenced test” even though it just means that it is the primarily intended interpretation.

Examples of Norm-Referenced vs. Criterion-Referenced

Suppose you received a score of 90% on a Math exam in school.  This could be interpreted in both ways.  If the cutscore was 80%, you clearly passed; that is the criterion-referenced interpretation.  If the average score was 75%, then you performed at the top of the class; this is the norm-referenced interpretation.  Same test, both interpretations.

What if the average score was 95%?  Well, that changes your norm-referenced interpretation (you are now below average) but the criterion-referenced interpretation does not change.

Now consider a certification exam.  This is an example of a test that is specifically designed to be criterion-referenced.  It is supposed to measure that you have the knowledge and skills to practice in your profession.  It doesn’t matter whether all candidates pass or only a few candidates pass; the cutscore is the cutscore.

However, you could interpret your score by looking at your percentile rank compared to other examinees; it just doesn’t impact the cutscore

On the other hand, we have an IQ test.  There is no criterion-referenced cutscore of whether you are “smart” or “passed.”  Instead, the scores are located on the standard normal curve (mean=100, SD=15), and all interpretations are norm-referenced.  Namely, where do you stand compared to others?

Is this impacted by item response theory (IRT)?

If you have looked at item response theory (IRT), you know that it scores examinees on what is effectively the standard normal curve (though this is shifted if Rasch).  But, IRT-scored exams can still be criterion-referenced.  It can still be designed to measure a specific body of knowledge and have a cutscore that is fixed and stable over time.

Even computerized adaptive testing can be used like this.  An example is the NCLEX exam for nurses in the United States.  It is an adaptive test, but the cutscore is -0.18 (NCLEX-PN on Rasch scale) and it is most definitely criterion-referenced.

Building and validating an exam

The process of developing a high-quality assessment is surprisingly difficult and time-consuming. The greater the stakes, volume, and incentives for stakeholders, the more effort that goes into developing and validating.  ASC’s expert consultants can help you navigate these rough waters.

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Nathan Thompson, PhD

CEO at Assessment Systems
Nathan Thompson, PhD, is CEO and Co-Founder of Assessment Systems Corporation (ASC). He is a psychometrician, software developer, author, and researcher, and evangelist for AI and automation. His mission is to elevate the profession of psychometrics by using software to automate psychometric work like item review, job analysis, and Angoff studies, so we can focus on more innovative work. His core goal is to improve assessment throughout the world. Nate was originally trained as a psychometrician, with an honors degree at Luther College with a triple major of Math/Psych/Latin, and then a PhD in Psychometrics at the University of Minnesota. He then worked multiple roles in the testing industry, including item writer, test development manager, essay test marker, consulting psychometrician, software developer, project manager, and business leader. He is also cofounder and Membership Director at the International Association for Computerized Adaptive Testing (iacat.org). He's published 100+ papers and presentations, but his favorite remains https://scholarworks.umass.edu/pare/vol16/iss1/1/.

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