Date of Award

Fall 2021

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)



First Advisor

Hoelzle, James

Second Advisor

Saunders, Stephen

Third Advisor

Nielson, Kristy


Somatization, the propensity to experience emotional distress as physical symptoms, is a psychological issue associated with poor health outcomes. While somatic symptom reporting is quantified by various instruments, relatively little is known regarding the psychometric properties of these scales. The purpose of this study is to examine the psychometric properties of the Personality Assessment Inventory (PAI; Morey, 1991/2007) Somatic Complaints (SOM) scale in a clinical population. The properties of the SOM scale were evaluated through bifactor confirmatory factor analysis (CFA) and item response theory (IRT) procedures. A bifactor SOM model exhibited excellent fit and consisted of a general Somatic Complaints factor and subfactors reflecting SOM subscales, Health Concerns, Conversion, and Somatization. Bifactor graded item response model analyses elucidate how each specific SOM item is related to a broad somatoform construct. Particularly, items with high discrimination and moderate difficulty reflect more general comments about health status and are adequate measures of somatic complaints. In contrast, items with significantly high or low difficulty and low discrimination reflected uncommon and unusual somatic symptoms Additionally, bifactor IRT results revealed that SOM most efficiently quantifies somatic symptom reporting between T scores of 55 to 70. Collectively, this research furthers our understanding of SOM, effectively increasing our clinical understanding of somatization and the overall utility of the scale.


Restricted Access Item

Having trouble?