Development and Testing of an Abbreviated Numeracy Scale: A Rasch Analysis Approach

Area of Science:

• Cognitive Psychology
• Decision Science
• Psychometrics

Background:

• Individual differences in numeracy significantly impact decision-making.
• Existing measures of numeracy may lack psychometric robustness or breadth.
• Understanding numerical information, including probabilities, is crucial for informed choices.

Purpose of the Study:

• To develop and validate a shorter, psychometrically improved measure of numeracy.
• To assess the predictive validity of the new numeracy scale against decision-making preferences and risk judgments.
• To present comprehensive psychometric properties of numeracy measures across diverse populations.

Main Methods:

• Rasch analysis was employed on an 18-item pool from existing numeracy measures.
• An eight-item numeracy scale was developed and validated across two large, independent samples.
• Predictive validity was tested by comparing the new scale's performance against previous measures in relation to decision-making and risk judgments.

Main Results:

• A refined eight-item numeracy scale was created, demonstrating a broader difficulty range.
• The new Rasch-based numeracy scale showed superior predictive validity for decision-making preferences and risk judgments compared to prior measures.
• The study provides the first psychometric evaluation of popular numeracy measures across varied age and educational demographics.

Conclusions:

• The developed Rasch-based numeracy scale offers a psychometrically sound and efficient tool for research.
• This improved measure enhances our understanding of the association between numeracy and decision processes.
• The scale's validity across diverse populations makes it suitable for wide application in psychological and economic research.