Mitra Rahimzadeh, Noushin Ghavidel, Behrooz Kavehie,
Volume 28, Issue 5 (12-2025)
Abstract
Introduction: The age structure of the population has changed due to a decrease in mortality rates. With the increase in the number of elderly individuals, addressing their physical, mental, and social needs has become essential. It is necessary to have a reliable and valid tool for assessing the health status of this group for developing future policies and planning health interventions. This study aimed to evaluate the psychometric properties of Lali’s Healthy Lifestyle Questionnaire using Item Response Theory (IRT) among the elderly in Karaj City.
Methods: Data collection was done through the distribution of questionnaires and interviews with patients in the health centers of Karaj city. In addition to demographic information, Lali's Healthy Lifestyle Questionnaire (2012) was used to collect data.
Results: The mean (standard deviation) age of the participants in the study was 66.82 (6.59) years. Based on the Akaike Information Criterion (AIC), the Nominal Response Model (NRM) demonstrated a better fit to the data among the common IRT models for Likert-scale questionnaires. Based on this model, out of the 54 items used, 6 items did not meet the acceptable criteria for the discrimination parameter and were excluded from the questionnaire. Based on the total information function, the questionnaire can appropriately differentiate individuals within the ability range of -1.5 to 2.5.
Conclusions: Using Item Response Theory in questionnaire psychometrics helps to reduce the number of unrelated items and increase the accuracy of the measurement tools.
