Physical Symptoms Inventory (PSI)

Abstract

The Physical Symptoms Inventory (PSI) is a widely utilized self-report measure designed to assess the frequency of various physical complaints or symptoms experienced by an individual, typically within a defined time frame (e.g., the past 30 days). Developed primarily within the field of Occupational Health Psychology, the PSI serves as a key indicator of psychological and physical strain resulting from workplace stressors. It is often employed alongside other measures of job demands and constraints (such as the Interpersonal Conflict at Work Scale, Organizational Constraints Scale, and Quantitative Workload Inventory) to provide a comprehensive view of the stress process and its somatic manifestations.

Keywords

Physical Symptoms Inventory, PSI, occupational stress, psychological strain, physical strain, job stressors, self-report, somatic symptoms.

Authors

Paul E. Spector, Steven M. Jex

Purpose

The primary purpose of the PSI is to quantify the degree of physical strain experienced by respondents. The scale captures the somatic manifestation of stress, providing data on physiological disruption that may result from chronic exposure to adverse work environments. This makes it particularly valuable in studies examining the relationship between specific organizational and environmental demands and subsequent health outcomes.

The PSI is designed to be a brief, non-diagnostic tool for assessing general physical distress, making it suitable for large-scale organizational surveys and research on employee well-being. By focusing on common, self-reported symptoms, the instrument helps researchers establish a direct link between perceived work demands and measurable health consequences.

Construct

The PSI measures the construct of Physical Strain, defined as the adverse physiological responses and symptoms that occur as a consequence of exposure to demanding or negative environmental stimuli, particularly those encountered in the workplace. This construct reflects the body’s reaction to chronic psychological distress, manifesting in various non-specific physical ailments.

The items cover a broad range of common physical complaints, including gastrointestinal issues, musculoskeletal pain, sleep disturbances, and general fatigue, which are frequently identified in the literature as being associated with high levels of psychological stress and burnout. The total score represents the cumulative burden of physical symptoms reported by the individual.

Validity

The PSI has demonstrated acceptable psychometric properties across numerous organizational studies. Construct validity is supported by consistent findings showing significant correlations with established measures of organizational demands (e.g., workload, organizational constraints) and other indicators of psychological strain (e.g., anxiety, depression).

Further evidence of validity comes from its ability to discriminate effectively between groups known to experience different levels of workplace stress. The scale is sensitive to changes in work environments, suggesting strong concurrent and predictive validity when used in longitudinal studies of stress intervention effectiveness.

Reliability

Reliability, typically assessed via internal consistency, has been consistently reported as strong for the PSI. In the original development study (Spector & Jex, 1998) and subsequent applications, the Cronbach’s alpha coefficient for the scale typically exceeds the .80 threshold, often reaching the high .80s or low .90s.

This high internal consistency indicates that the items reliably measure a single, coherent underlying construct of general physical strain. While test-retest reliability is less frequently reported, the scale is designed to capture fluctuations in strain over time, making cross-sectional reliability (internal consistency) the primary measure of its consistency.

Factor Analysis

Although the scale includes a diverse set of symptoms, the PSI is generally treated as a unidimensional measure of overall physical strain in most applied research. Exploratory and confirmatory factor analyses, as documented in the original validation research, typically support a strong single-factor structure.

This single-factor model suggests that the common variance among the items reflects a general state of physiological distress resulting from environmental stressors, rather than distinct, uncorrelated clusters of symptoms (e.g., separating gastrointestinal issues from muscular pain).

Instrument

Test Type: Self-report psychological inventory

Format: Multiple versions available (18-item, 13-item, and 12-item versions). Response formats vary depending on the version, utilizing either a frequency scale or a binary occurrence scale with medical follow-up.

Language Available: English (Primary language of development); translations may exist but are not specified in the source.

Population Group: Working adults and employees

Age Group: Adult (typically 18 years and older)

Population Details: Used extensively in organizational, occupational, and health psychology research settings globally to assess strain outcomes related to work demands.

Test Methodology: Retrospective self-assessment, asking respondents to report the occurrence or frequency of symptoms over a specific time period (e.g., the last 30 days).

Keywords

Spector, Jex, strain measurement, job demands-resources model, psychosomatic symptoms, organizational psychology, stress assessment.

Authors

Author ORCID Identifier: N/A (Not provided in source material)

Affiliation Email addresses: N/A (Not provided in source material)

Correspondence Address: Correspondence is typically directed through the University of South Florida, Department of Psychology, associated with Dr. Paul E. Spector.

Permissions & Fee and Test Year

The PSI was formally published in 1998 as part of the development of four job stressor and strain measures. The scale is generally available for non-commercial research and educational use, provided the source is properly cited. Users should consult the author’s official website for current licensing terms and conditions. The conditions for using these assessments can be reviewed here: http://paulspector.com/scales/our-assessments/conditions-for-using-these-assessments/

Reference’s

• Bollen‚ K.‚ & Lennox‚ R. (1991). Conventional wisdom on measurement: A structural equation perspective. Psychological Bulletin‚ 110‚ 305-314.

• Keenan‚ A.‚ & Newton‚ T. J. (1985). Stressful events‚ stressors‚ and psychological strains in young professional engineers. Journal of Occupational Behavior‚ 6‚ 151-156.

• Peters‚ L. H.‚ & O’Connor‚ E. J. (1980). Situational constraints and work outcomes: the influences of a frequently overlooked construct. Academy of Management Review‚ 5‚ 391-397.

• 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.

Items of the Physical Symptoms Inventory (PSI)

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

18-item Version

During the past 30 days did you have?

1. An upset stomach or nausea
2. A backache
3. Trouble sleeping
4. A skin rash
5. Shortness of breath
6. Chest pain
7. Headache
8. Fever
9. Acid indigestion or heartburn
10. Eye strain
11. Diarrhea
12. Stomach cramps (Not menstrual)
13. Constipation
14. Heart pounding when not exercising
15. An infection
16. Loss of appetite
17. Dizziness
18. Tiredness or fatigue

13-item Version

1. An upset stomach or nausea
2. A backache
3. Trouble sleeping
4. 4 Headache
5. Acid indigestion or heartburn
6. Eye strain
7. Diarrhea
8. Stomach cramps (Not menstrual)
9. Constipation
10. Ringing in the ears
11. Loss of appetite
12. Dizziness
13. Tiredness or fatigue

12-item Version

1. An upset stomach or nausea
2. Trouble sleeping
3. Headache
4. Acid indigestion or heartburn
5. Eye strain
6. Diarrhea
7. Stomach cramps (Not menstrual)
8. Constipation
9. Ringing in the ears
10. Loss of appetite
11. Dizziness
12. Tiredness or fatigue

Response Options for 18-item Version:

• No
• Yes, but I didn’t see doctor
• Yes, and I saw doctor

Response Options for 12 & 13-item Version (Frequency Scale):

• Not at all
• Once or Twice
• Once or twice per week
• Most days
• Every day