Item response theory in affective instrument development: an illustration

Area of Science:

• Nursing Research
• Psychometrics
• Educational Measurement

Background:

• Item Response Theory (IRT) analysis is crucial for establishing construct validity in instrument development.
• IRT provides detailed interpretations of respondent performance, differentiating between low- and high-scoring individuals.
• A key IRT function is evaluating how well items assess the underlying attitude continuum within an instrument.

Purpose of the Study:

• To introduce nurse researchers to the benefits of IRT in developing affective instruments.
• To describe the Facets computer program, a tool for conducting IRT analysis.
• To illustrate the application of IRT using real-world data.

Main Methods:

• The study utilizes the Facets program, which employs a one-parameter Rasch measurement model (item difficulty).
• Data from a survey of 525 new mothers were analyzed.
• The psychometric properties of the Postpartum Depression Screening Scale were assessed using Facets.

Main Results:

• The Facets program effectively demonstrated the utility of IRT in analyzing the Postpartum Depression Screening Scale.
• The analysis provided empirical support for the construct validity of the scale.
• The results highlighted the potential for finer construct interpretations and descriptions of respondent performance.

Conclusions:

• IRT analysis, facilitated by programs like Facets, is a valuable yet underutilized approach in affective instrument development for nursing research.
• Increased awareness and adoption of IRT can enhance the quality and interpretability of affective measures.
• The study advocates for greater prominence of IRT in nursing research to improve instrument development and data interpretation.