The PSI assesses physical, somatic health symptoms thought by stress researchers to be associated with psychological distress. Each is a condition/state about which a person would likely be aware, e.g., headache. The scale has evolved over time. The original contains 18 items. (See Spector & Jex, 1998 about additional omitted items). Respondents are asked to indicate for each symptom if they didn’t have it, had it, or saw a doctor for it in the past 30 days. Three scores are computed, the number of symptoms they had (have symptoms), the number for which they saw a doctor (doctor symptoms), and sum of both (total). Possible scores range from 0 to 18. More recently we have shortened the scale to 12 items, and changed the response choices to frequency ranging from “never” to “every day”. We eliminated 5 items that were rarely endorsed, and one item (backache) because it overlapped with musculoskeletal disorder (MSD). Copies of the original 18-item and the newer 12-item versions are on this website. As with the OCS, this is a causal indicator scale, for which coefficient alpha is irrelevant.
Spector, P. E., & Jex, S. M. (1998). Development of Four Self-Report Measures of Job Stressors and Strain: Interpersonal Conflict at Work Scale, Organizational Constraints Scale, Quantitative Workload Inventory, and Physical Symptoms Inventory. Journal of Occupational Health Psychology, 3, 356-367.
Scoring
For the 18-item version each item has three response choices, ranging from 1 to 3. The have symptom score is computed by adding the number of 2 responses, and the doctor symptom score is computed by adding the number of 3 responses. The total symptom score is the sum of the other two scores, or the sum of all 2 and 3 responses. The possible range is 0 to 18 for each scale, but the total symptom score must be the sum of the other two scales. For the 12 and 13-item versions, there are five response choices, ranging from 1 (not at all) to 5 (every day). Sum responses to all of the items into a total score, which can range from 12 to 60.
PSI 18-item and stressor scales. The PSI in its original yes/no format.
PSI 12-item. Removed item about backache when we use it with the Nordic Musculoskeletal Disorder scale
PSI 13-Item Removed 5 items seldom endorsed by people and changed to frequency format.
Note: The PSI is copyright © 1997, Paul E. Spector and Steve M. Jex, All rights reserved.