Functional Independence Measure (FIM)

Abstract

The Functional Independence Measure (FIM) is an 18-item, clinician-rated assessment battery designed to quantify physical, cognitive, and social functional independence in individuals recovering from severe illness, injury, or disabling neurotrauma. Conceived in the mid-1980s by a national task force led by Robert A. Keith, Carl V. Granger, and Byron B. Hamilton, the instrument addresses the historical absence of a uniform, scientifically sound metric for rehabilitation outcomes. The scale evaluates disability based on the objective burden of care—specifically, the degree of assistance, device adaptation, and time required for a patient to execute foundational daily activities. Composed of two primary subscales—the 13-item Motor subscale and the 5-item Cognitive subscale—the FIM encompasses six specific functional domains: Self-Care, Sphincter Control, Transfers, Locomotion, Communication, and Social Cognition. Each item is scored across an authentic seven-point ordinal gradient extending from 1 (Total Assistance / Complete Dependence, where the individual expends less than 25% of the effort) to 7 (Complete Independence, where the individual acts safely, in a timely manner, and without assistance or devices). Total raw scores range between 18 and 126, with higher values denoting greater functional independence and lower demands placed on personal caregivers or institutional healthcare resources. Extensive psychometric evaluations utilizing classical test theory and item response theory (notably Rasch measurement models) demonstrate exceptional internal consistency (Cronbach’s alpha often exceeding .93 for the motor domain and .86 for the cognitive domain), strong interrater reliability (intraclass correlation coefficients typically between .80 and .95), and high responsiveness to changes occurring over inpatient rehabilitation cycles. Consequently, the FIM served for decades as the international gold standard in rehabilitation benchmarking, program evaluation, and clinical policy formulation.

Keywords

Functional Independence Measure, FIM, activities of daily living, rehabilitation psychometrics, burden of care, motor functional assessment, cognitive impairment, Rasch analysis, disability evaluation, neurorehabilitation, outcome measurement, Barthel Index, physical medicine

Authors

The development of the Functional Independence Measure was initiated under the auspices of a national task force co-sponsored by the American Congress of Rehabilitation Medicine (ACRM) and the American Academy of Physical Medicine and Rehabilitation (AAPM&R). The core development team included:

• Robert A. Keith, Ph.D. — Research Department, Casa Colina Hospital for Rehabilitative Medicine, Pomona, California, USA.
• Carl V. Granger, M.D. — Department of Rehabilitation Medicine, State University of New York (SUNY) at Buffalo School of Medicine and Biomedical Sciences, Buffalo, New York, USA.
• Byron B. Hamilton, M.D., Ph.D. — Department of Rehabilitation Medicine, State University of New York at Buffalo, Buffalo, New York, USA.
• Frank S. Sherwin, M.D. — Rehabilitation Institute of Chicago, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.

Institutional stewardship and longitudinal data warehousing were later managed by the Uniform Data System for Medical Rehabilitation (UDSMR), established at the University at Buffalo Foundation (Buffalo, New York, USA).

Purpose

The fundamental purpose of the Functional Independence Measure (FIM) is to provide an objective, uniform, and standardized measurement of physical, psychological, and social performance in daily life, calibrated directly to the “burden of care.” Before the inception of the FIM, the discipline of physical medicine and rehabilitation was encumbered by an array of non-standardized clinical scales. Existing assessment instruments, such as the Barthel Index and the Katz Index of Independence in Activities of Daily Living, focused heavily on physical tasks, frequently exhibited substantial ceiling or floor effects, and lacked the psychometric refinement needed to capture subtle gains achieved through rigorous multidisciplinary rehabilitation. The FIM was systematically constructed to resolve these methodological deficiencies by creating an empirically unified language for clinicians, researchers, and health policy administrators.

From a clinical perspective, the FIM fulfills several critical operational functions:

• Baseline Functional Triage: It allows multidisciplinary rehabilitation teams—comprising physiatrists, physical therapists, occupational therapists, speech-language pathologists, and rehabilitation nurses—to quantify an incoming patient’s functional impairments within the first 72 hours of admission.
• Goal Formulation and Care Planning: By delineating exactly which tasks require total, moderate, or minimal human assistance, clinical teams can establish realistic, milestone-based therapeutic interventions targeted at reducing the human and mechanical resources a patient requires upon discharge.
• Longitudinal Trajectory Monitoring: The scale enables continuous tracking of functional trajectory during an inpatient stay, facilitating mid-course clinical corrections if anticipated progress stalls.
• Post-Discharge Prognostication: Raw and Rasch-transformed FIM scores correlate robustly with post-discharge placement viability (e.g., community living, assisted living, or long-term nursing care) and can predict the number of daily human caregiver hours an individual will require at home.

In the context of health systems and research, the FIM functions as an indispensable program-evaluation metric. Aggregated FIM data across thousands of facilities through the UDSMR repository have driven national benchmarks for clinical efficiency, length of stay (LOS), and cost-effectiveness. In many healthcare jurisdictions—most prominently in the United States under the Centers for Medicare & Medicaid Services (CMS) Inpatient Rehabilitation Facility Prospective Payment System (IRF-PPS)—FIM-derived Case Mix Groups (CMGs) historically dictated Medicare reimbursement schedules, underscoring its central role at the nexus of clinical psychometrics and healthcare economics.

Psychological Construct

The Functional Independence Measure assesses the latent psychological and biological construct of functional independence, operationalized as an individual’s operational capacity to perform essential personal activities safely and autonomously within physical, cognitive, and social spheres. Unlike measures of biological pathology or neuromuscular impairment (such as electromyographic nerve conduction, manual muscle testing, or radiographic tissue imaging), the FIM does not gauge physiological capacity in isolation. Instead, it captures actual performance in real-world contexts, defining disability primarily by the interpersonal and physical assistance a person requires from another human being.

The overall construct is partitioned into two distinct, hierarchically organized, yet correlated latent dimensions:

1. The Motor Functional Dimension (13 Items)

The Motor dimension encompasses physical actions essential to somatic integrity and personal mobility. This domain reflects an individual’s biomechanical proficiency, postural stability, kinetic execution, and physiological control. It is composed of four primary sub-domains:

• Self-Care: Evaluates tasks including Eating (the ability to manipulate eating utensils, bring nourishment to the mouth, chew, and swallow safely), Grooming (oral hygiene, hair care, washing face and hands, and shaving or cosmetics application), Bathing (washing, rinsing, and drying the body from the neck down in a shower or tub), Dressing—Upper Body (putting on and removing clothes above the waist, including orthoses or prostheses), Dressing—Lower Body (donning/doffing garments from the waist down, including socks and footwear), and Toileting (managing clothes and perineal hygiene before and after voiding).
• Sphincter Control: Assesses the physiological mastery and behavioral self-management of excretory functions, divided into Bladder Management (urinary continence, safe scheduling, clean intermittent catheterization, or management of external collection devices) and Bowel Management (bowel control, management of suppository routines, colostomy maintenance, and avoidance of accidental soiling).
• Transfers: Evaluates kinetic positional transitions, including Bed, Chair, Wheelchair Transfer (moving safely between surfaces, including attaining a standing position if ambulatory), Toilet Transfer (seating and rising from a toilet safely), and Tub, Shower Transfer (navigating the physical thresholds of a bathtub or shower stall).
• Locomotion: Measures displacement across spatial environments via Walking or Using a Wheelchair (locomoting across a level surface for at least 150 feet) and traversing Stairs (ascending and descending 12 to 14 indoor steps safely).

2. The Cognitive Functional Dimension (5 Items)

The Cognitive dimension measures neuropsychological functions necessary to process environmental information, engage in reciprocal communication, solve daily problems, and navigate social relationships. This dimension reflects practical executive function, working memory, pragmatics, and emotional self-regulation, structured into two sub-domains:

• Communication: Assesses receptive and expressive language through Comprehension (processing auditory or visual language, following directions, understanding social nuance) and Expression (intelligible vocal articulation, non-vocal language production, or functional utilization of augmentative communication technology).
• Social Cognition: Captures neurobehavioral and executive competencies through Social Interaction (acting appropriately with peers, staff, and family members, controlling impulsive, aggressive, or withdrawn behaviors), Problem Solving (identifying daily hazards, initiating logical multi-step solutions, managing financial or medication decisions, and practicing self-correction), and Memory (retaining and retrieving information essential for institutional safety and community functioning, including recognizing familiar faces, keeping appointments, and executing daily schedules).

Theoretical Framework

The theoretical architecture of the Functional Independence Measure is anchored in biomedical sociology and contemporary rehabilitation theory, drawing directly from the disablement models articulated by Saad Nagi (1965) and the World Health Organization’s classic International Classification of Impairments, Disabilities, and Handicaps (ICIDH, 1980), which later evolved into the International Classification of Functioning, Disability and Health (ICF, 2001).

Nagi’s conceptual framework posited four interrelated yet distinct operational strata:

1. Active Pathology: Interruption or interference with normal physiological processes (e.g., acute cerebrovascular ischemic infarction, spinal cord transection).
2. Impairment: Anatomical, physiological, mental, or emotional abnormalities or losses occurring at the organ or system level (e.g., hemiparesis, dysphasia, spasticity).
3. Functional Limitation: Constraints in individual performance and execution of tasks at the whole-person level (e.g., inability to walk, write, or comprehend spoken instructions).
4. Disability: Patterns of behavior that emerge when functional limitations restrict the performance of socially defined roles and activities within a specific socio-physical environment.

The FIM was designed to operate primarily at the level of Functional Limitation and Disability. The developers maintained that medical pathologies and physiological impairments, while clinically critical, fail to capture the ecological reality of a patient’s life. Two patients presenting with identical structural brain lesions on magnetic resonance imaging might demonstrate vastly disparate capabilities in self-care, mobility, and community participation due to differences in compensatory mechanisms, learned skills, emotional resilience, and assistive device integration.

Crucially, the theoretical bedrock of the FIM is the Burden of Care concept. Granger and colleagues conceptualized disability not as a static biological deficit, but as a quantifiable drain on external human and mechanical resources. Burden of care represents the operational “cost” of a disability, measurable through the proxy metric of caregiver time, physical effort, and personal intervention needed to sustain the patient’s daily survival. By formalizing this relationship into a seven-point ordinal gradient across 18 items, the FIM provides an operational link between functional psychometrics, clinical interventions, and healthcare utilization.

From a psychometric modeling perspective, the FIM is grounded in Item Response Theory (IRT), specifically the Rasch measurement model. Rather than assuming that all items impose an equivalent difficulty threshold on a patient, the theoretical framework treats functional independence as a continuous latent trait ($\theta$). A patient with a specific level of underlying ability has a mathematically predictable probability of achieving a specific score on any item, given that item’s calibrated intrinsic difficulty (e.g., eating is inherently less difficult than negotiating stairs; simple auditory comprehension is less difficult than complex executive problem solving).

Validity

The psychometric validity of the Functional Independence Measure has been investigated across a range of diagnostic cohorts, including stroke, traumatic brain injury (TBI), spinal cord injury (SCI), multiple sclerosis, orthopedic fractures, and non-traumatic geriatric conditions.

Construct Validity

Construct validity has been demonstrated through convergent and discriminant validity testing, as well as structural hypothesis verification. In convergent validity studies, the FIM Motor subscale correlates strongly with established functional tools:

• Correlations with the Barthel Index consistently range from $r = .84$ to $r = .95$, demonstrating strong construct convergence while FIM provides superior granularity at both ends of the performance continuum.
• Correlations with the Katz ADL Scale similarly range between $r = .75$ and $r = .88$.
• Conversely, discriminant validity is substantiated by lower correlations observed between the FIM Motor domain and purely cognitive or psychological assessments, such as the Mini-Mental State Examination (MMSE; typically $r = .15$ to $.35$), confirming that the Motor subscale isolates biomechanical and physical independence rather than general global cognitive functioning.
• The FIM Cognitive subscale shows convergent validity with formal neuropsychological batteries, yielding moderate-to-strong correlations with the Neurobehavioral Cognitive Status Examination (Cognistat) and selected subtests of the Wechsler Adult Intelligence Scale ($r = .50$ to $.70$).

Predictive and Criterion Validity

Predictive validity is well established. Initial admission FIM scores serve as powerful prospective indicators of key rehabilitation milestones:

• Discharge Destination: Logistic regression models indicate that admission Motor FIM scores significantly predict whether a patient will be discharged home versus institutionalized into a skilled nursing facility (odds ratios often exceeding 1.05 per single-point raw score increase; $p < .001$).
• Length of Stay (LOS): Inpatient rehabilitation duration is inversely related to admission FIM scores when controlling for medical complexity, showing correlation coefficients between $r = -.45$ and $r = -.60$.
• Caregiver Burden in the Community: Longitudinal follow-up studies measuring formal and informal caregiving demonstrate a strong linear relationship: each point increase on the discharge FIM corresponds to a measurable reduction in daily caregiver assistance minutes ($r = -.65$ to $-.78$), validating the central theoretical premise of the tool.

Responsiveness to Change

The FIM demonstrates high responsiveness (sensitivity to change) over the course of acute and subacute rehabilitation. Calculation of effect sizes (Cohen’s $d$) and standardized response means (SRM) across inpatient stays routinely yields values between $0.80$ and $1.50$ for the Motor subscale, reflecting large, clinically meaningful gains. The Minimal Clinically Important Difference (MCID) has been empirically calibrated across stroke populations as approximately 22 points for the total FIM, 17 points for the Motor subscale, and 3 points for the Cognitive subscale.

Reliability

The reliability of the FIM has been thoroughly documented in observational studies, multi-center trials, and systematic meta-analyses.

Interrater Reliability

A landmark meta-analysis conducted by Ottenbacher et al. (1996), synthesizing 11 separate peer-reviewed investigations spanning 1,568 patients, identified an overall pooled median interrater reliability intraclass correlation coefficient (ICC) of .95 for the Total FIM score. When analyzed at the subscale and item levels:

• The pooled median ICC for the Motor Subscale was .95 (range .88–.98).
• The pooled median ICC for the Cognitive Subscale was .89 (range .75–.95).
• Individual item kappa values ($kappa$) generally ranged between .53 and .88, indicating moderate to near-perfect agreement. The highest interrater concordances were routinely observed on high-visibility physical tasks (e.g., Eating, $kappa > .80$; Bed, Chair, Wheelchair Transfer, $kappa > .75$), whereas subjective cognitive evaluations exhibited slightly lower concordance (e.g., Social Interaction, $kappa = .53–.65$; Problem Solving, $kappa = .55–.68$).

Test-Retest Reliability

Test-retest stability has been demonstrated when evaluations are conducted across stable neurological patients over intervals of 48 to 72 hours. Pearson product-moment and intraclass correlation coefficients typically range from $r = .85$ to $.98$ for the total score. Motor items consistently exhibit stability coefficients above .90, whereas cognitive items demonstrate test-retest coefficients between .80 and .88.

Internal Consistency

Estimates of internal consistency via Cronbach’s alpha ($\alpha$) are consistently high:

• Total FIM Scale (18 items): $\alpha = .93\text{ to }.97$
• Motor Subscale (13 items): $\alpha = .91\text{ to }.95$
• Cognitive Subscale (5 items): $\alpha = .84\text{ to }.90$

These values demonstrate excellent item coherence without clinical redundancy. Item-total correlations for the motor tasks range between $.60$ and $.85$, while cognitive item-total correlations range between $.55$ and $.78$.

Factor Analysis

Extensive exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and Rasch latent trait modeling have been deployed to clarify the underlying structural dimensionality of the Functional Independence Measure.

Dimensionality: Unidimensional vs. Bidimensional Structure

While early clinical applications occasionally aggregated the 18 items into a single composite score, structural psychometric evaluations (e.g., Linacre et al., 1994; Heinemann et al., 1993; Wright et al., 1997) demonstrate that the FIM is bidimensional rather than strictly unidimensional:

• Motor Factor: Composed of the first 13 items spanning Self-Care, Sphincter Control, Transfers, and Locomotion. Exploratory factor analyses with principal component extraction and Promax/Varimax rotation indicate that these 13 items load onto a primary physical factor accounting for 55% to 65% of the total variance, with factor loadings ranging from $.68$ to $.91$.
• Cognitive Factor: Composed of the remaining 5 items spanning Communication and Social Cognition. These items load cleanly onto a distinct second factor, accounting for an additional 10% to 15% of the total variance, with factor loadings between $.65$ and $.87$. Cross-loadings between the motor and cognitive items are minimal (typically $< .25$).

Confirmatory factor analyses testing a two-factor correlated model (Motor and Cognitive) have confirmed acceptable model fit across large rehabilitation cohorts:

• Comparative Fit Index (CFI): Typically $ge .94$ to $.97$
• Tucker-Lewis Index (TLI): Typically $ge .93$ to $.96$
• Root Mean Square Error of Approximation (RMSEA): Values generally fall between $.05$ and $.07$, confirming acceptable fit for the two-dimensional model.

Rasch Measurement Model Calibrations

Because the FIM utilizes ordinal response steps, Rasch analysis has played an integral role in evaluating its rating scale mechanics and item hierarchical calibration. Rasch partial-credit modeling reveals that the 18 items can be calibrated along a single continuum of item difficulty only when the motor and cognitive domains are analyzed as separate latent subscales. Infit and outfit mean square (MnSq) statistics generally fall within the acceptable boundaries of 0.6 to 1.4 for clinical observational instruments.

Rasch item calibrations consistently rank the difficulty hierarchy of items across broad patient populations:

• Easiest Motor Items: Eating and Bowel Management consistently require the lowest latent motor functional ability to attain a score of 7.
• Most Difficult Motor Items: Stairs and Tub, Shower Transfer represent the highest difficulty thresholds, requiring greater neuromuscular stability, balance, and motor planning.
• Cognitive Item Hierarchy: Within the Cognitive subscale, Comprehension is calibrated as the easiest item, whereas Problem Solving and Memory emerge as the most challenging cognitive tasks.

Instrument / Measurement Tool

The Functional Independence Measure is a multidisciplinary, clinician-observed performance assessment. The core structural, administrative, and scoring parameters of the instrument are detailed below:

• Instrument Type: Clinician-rated observational rating scale and behavioral performance measure.
• Target Population: Adults receiving inpatient, outpatient, home-based, or long-term medical rehabilitation for neurological, musculoskeletal, orthopedic, or medical debility (a dedicated pediatric equivalent, the WeeFIM, exists for children aged 6 months to 7 years).
• Administration Modality: Multidisciplinary observation and clinical consensus. Physical therapists generally score locomotion and transfers; occupational therapists evaluate self-care and tub/shower transfers; speech-language pathologists assess comprehension, expression, and problem solving; and rehabilitation nurses typically document sphincter management, memory, and daytime social interaction.
• Administration Time: Baseline assessment occurs across the first 72 hours following inpatient admission; discharge evaluation is executed within the final 72 hours prior to discharge. Cumulative clinical scoring takes approximately 30 to 45 minutes of direct observational synthesis.
• Number of Items: 18 discrete functional items.
• Scale Dimensionality:
  • Motor Subscale: 13 items (Items 1 to 13).
  • Cognitive Subscale: 5 items (Items 14 to 18).
• Response Scale (Authentic 7-Point Gradient): Every item is scored from 1 to 7 based on the physical effort and assistance required:
  • Level 7: Complete Independence — The activity is performed safely, without modification, assistive devices, or aids, and within a reasonable time.
  • Level 6: Modified Independence — The activity requires an assistive device/aid, takes more than reasonable time, or poses safety/risk considerations.
  • Level 5: Supervision or Setup — The patient requires standby assistance, cuing, or coaxing without physical contact, or needs setup of items/application of orthoses.
  • Level 4: Minimal Contact Assistance — The patient performs 75% or more of the effort; helper provides touching/steadying assistance only.
  • Level 3: Moderate Assistance — The patient performs 50% to 74% of the effort; helper provides more than physical touching.
  • Level 2: Maximal Assistance — The patient performs 25% to 49% of the effort; helper provides maximal physical assistance.
  • Level 1: Total Assistance — The patient performs less than 25% of the effort, or requires two helpers, or the activity is not performed.
• Scoring and Score Ranges:
  • Total FIM Score: 18 to 126.
  • Motor Subscale Score: 13 to 91.
  • Cognitive Subscale Score: 5 to 35.
  • Interpretation: No items are reverse-scored. Higher scores indicate greater functional independence and lower burden of care.

Permissions & Fee and Test Year

The development of the Functional Independence Measure was initiated in 1984, with formal field trials and landmark validation publications released in 1987 by Keith, Granger, Hamilton, and Sherwin under the sponsorship of the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.

Copyright and Proprietary Licensing: The FIM is a proprietary, copyrighted instrument owned and managed by the Uniform Data System for Medical Rehabilitation (UDSMR), a division of UB Foundation Activities, Inc., located in Amherst/Buffalo, New York, USA. The FIM is not open-access or public domain. Key operational terms include:

• Institutional Subscription and Fees: Healthcare facilities utilizing the FIM for clinical documentation, patient tracking, and outcomes benchmarking historically pay subscription or software licensing fees to UDSMR.
• Clinician Credentialing: To ensure high interrater reliability, UDSMR established an official credentialing process. Clinicians administering the tool must complete standardized instructional training and pass a proctored certification exam every two years to maintain rating validity.
• Research Permissions: Academic researchers wishing to utilize the FIM in formal clinical trials or research protocols must submit an application to UDSMR to obtain formal written permission and licensing agreements.
• Regulatory Transition: In United States inpatient rehabilitation facilities, the Centers for Medicare & Medicaid Services (CMS) officially phased out the FIM from the Inpatient Rehabilitation Facility Patient Assessment Instrument (IRF-PAI) effective October 1, 2019, replacing it with the CMS Section GG Functional Assessment Items (derived from the CARE tool) to standardize post-acute cross-setting metrics under the IMPACT Act of 2014. Despite this administrative transition in US federal reimbursement, the FIM remains an influential metric in longitudinal neurorehabilitation research, international healthcare systems, and historical clinical trials.

References

• Granger, C. V., Cotter, A. C., Hamilton, B. B., & Fiedler, R. C. (1990). Functional assessment scales: A study of persons with multiple sclerosis. Archives of Physical Medicine and Rehabilitation, 71(11), 870–875. PubMed: 2222153
• Granger, C. V., Hamilton, B. B., Keith, R. A., Zielezny, M., & Sherwin, F. S. (1986). Advances in functional assessment for medical rehabilitation. Topics in Geriatric Rehabilitation, 1(3), 59–74. https://doi.org/10.1097/00013614-198604000-00007
• Hamilton, B. B., Granger, C. V., Sherwin, F. S., Zielezny, M., & Tashman, J. S. (1987). A uniform national data system for medical rehabilitation. In M. J. Fuhrer (Ed.), Rehabilitation outcomes: Analysis and measurement (pp. 137–147). Paul H. Brookes Publishing Co.
• Heinemann, A. W., Linacre, J. M., Wright, B. D., Hamilton, B. B., & Granger, C. (1993). Relationships between impairment and physical independence as measured by the Functional Independence Measure. Archives of Physical Medicine and Rehabilitation, 74(6), 566–573. https://doi.org/10.1016/0003-9993(93)90153-2
• Keith, R. A., Granger, C. V., Hamilton, B. B., & Sherwin, F. S. (1987). The Functional Independence Measure: A new tool for rehabilitation. In P. E. Eisenberg, R. L. Glueckauf, & H. H. Zaretsky (Eds.), Medical aspects of disability: A handbook for the rehabilitation professional (pp. 6–18). Springer.
• Linacre, J. M., Heinemann, A. W., Wright, B. D., Granger, C. V., & Hamilton, B. B. (1994). The structure and stability of the Functional Independence Measure. Archives of Physical Medicine and Rehabilitation, 75(2), 127–132. https://doi.org/10.1016/0003-9993(94)90384-8
• McDowell, I. (2006). Measuring health: A guide to rating scales and questionnaires (3rd ed.). Oxford University Press. https://doi.org/10.1093/acprof:oso/9780195165678.001.0001
• Nagi, S. Z. (1965). Some conceptual issues in disability and rehabilitation. In M. B. Sussman (Ed.), Sociology and rehabilitation (pp. 100–113). American Sociological Association.
• Ottenbacher, K. J., Hsu, Y., Granger, C. V., & Fiedler, R. C. (1996). The reliability of the Functional Independence Measure: A quantitative review. Archives of Physical Medicine and Rehabilitation, 77(12), 1226–1232. https://doi.org/10.1016/s0003-9993(96)90184-7
• Wright, B. D., Linacre, J. M., & Heinemann, A. W. (1997). Measuring functional status in rehabilitation: Rasch analysis of the Functional Independence Measure. Archives of Physical Medicine and Rehabilitation, 78(3), 263–269. https://doi.org/10.1016/s0003-9993(97)90033-2

13. Items of the Scale (Questionnaire)