An overview of the Normal Ogive Harmonic Analysis Robust Method (NOHARM) approach to item response theory

Abstract

Here we provide a description of the IRT estimation method known as Normal Ogive Harmonic Analysis Robust Method (NOHARM). Although in some ways this method has been superseded by new computer programs that also adopt a specifically factor-analytic approach, its fundamental principles remain useful in certain applications, which include calculating the residual covariance matrix and rescaling the distribution of the common factor (latent trait). These principles can be applied to parameter estimates obtained by any method.

Keywords

• Factor analysis
• Item response theory
• Psychometrics