Female Orgasm Scale

1. Abstract

The Female Orgasm Scale (FOS), developed by University of Western Ontario researchers Alexandra McIntyre-Smith and William A. Fisher, is a psychometrically validated self-report instrument designed to capture the behavioral nuances, anatomical specificity, and affective evaluations characteristic of female orgasmic experience during partnered sexual activity. Traditional sexual health inventories, such as the Female Sexual Function Index (FSFI), frequently aggregate orgasmic frequency into broad indices that fail to differentiate between varying modalities of sexual stimulation. The FOS directly resolves this limitation by evaluating orgasm consistency across five distinct sexual contexts: penile-vaginal intercourse without direct clitoral contact, intercourse accompanied by simultaneous clitoral stimulation, partner-administered manual genital stimulation, partnered self-stimulation, and partner-administered oral genital stimulation (cunnilingus). In addition to contextual orgasmic consistency, the scale evaluates subjective cognitive-affective satisfaction with both the quantitative frequency and the qualitative experience of orgasms.

Comprising seven items structured across two empirically derived subscales—Orgasm from Clitoral Stimulation (Items 2–5) and Satisfaction with Orgasm (Items 6–7), with Item 1 standing as an independent index of coitus-dependent orgasmic consistency—the instrument employs an 11-point percentage-frequency metric (0% to 100% in 10% increments) and a 7-point satisfaction Likert scale. A standardized differential weighting algorithm scales all responses to a comparable metric for composite scoring. Across a rigorous three-study iterative development paradigm with sexually active female undergraduate cohorts, the FOS demonstrated robust psychometric properties: high internal consistency (α = .84–.86 for the total scale; α = .81–.82 for Clitoral Stimulation; α = .72–.90 for Satisfaction), excellent 4-week test-retest reliability (r = .82 for total score; r = .62–.78 for subscales), high convergent validity with the FSFI Orgasm subscale (r = .71), and distinct discriminant validity against social desirability and psychological distress markers. The FOS stands as a critical measurement tool in sexological research and clinical sexual medicine, providing an anatomically informed methodology for disaggregating physical stimulation modality from subjective orgasmic appraisal.

2. Keywords

Female Orgasm Scale, female sexual function, clitoral stimulation, orgasmic consistency, sexual satisfaction, psychometrics, sexual health assessment, anorgasmia, female sexual response, partnered sexual activity

3. Authors

The Female Orgasm Scale was conceptualized, developed, and validated by Alexandra McIntyre-Smith, Ph.D., and William A. Fisher, Ph.D. at the Department of Psychology, The University of Western Ontario (London, Ontario, Canada). Dr. William A. Fisher is a Distinguished Professor Emeritus of Psychology and Obstetrics and Gynaecology, recognized globally for his contributions to the Information-Motivation-Behavioral Skills (IMB) model of health behavior and extensive research in human sexuality, reproductive health, and sexual pharmacology.

Institutional contact correspondence historically associated with the development of the measure includes the Department of Psychology, The University of Western Ontario, London, Ontario, Canada N6A 5C2 (e-mail: [email protected] or [email protected]).

4. Purpose

The primary purpose of the Female Orgasm Scale is to provide an anatomically sensitive, empirically robust measurement tool that quantifies the consistency of female orgasm across distinct partnered sexual behaviors while decoupling functional orgasmic frequency from subjective orgasmic satisfaction. For decades, empirical investigations into female sexual health were constrained by heteronormative assumptions regarding intercourse, frequently presuming that penile-vaginal penetration constitutes the normative or primary vehicle for female sexual climax. Epidemiological and physiological research has conclusively established that the majority of women do not consistently reach orgasm via penile-vaginal intercourse alone, instead requiring direct, rhythmic stimulation of the external clitoris. Despite this biological reality, standard diagnostic and assessment protocols have historically conflated “difficulty reaching orgasm” with an inability to climax through coitus, leading to clinical over-pathologization and distorted empirical outcomes.

In clinical practice, the FOS serves as an invaluable diagnostic and evaluative tool for healthcare providers, sex therapists, and clinical psychologists addressing Female Orgasmic Disorder (FOD) as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The DSM-5 diagnostic criteria require a marked delay in, marked infrequency of, or absence of orgasm, or a markedly reduced intensity of orgasmic sensations, occurring on approximately 75% to 100% of occasions of sexual activity, accompanied by clinically significant personal distress. Importantly, the diagnostic manual explicitly specifies that clinicians must consider whether the stimulation provided is adequate in focus, intensity, and duration. By disaggregating orgasm rates across five specific behavioral modalities—ranging from unassisted penetration to explicit manual, oral, and self-directed clitoral stimulation in the presence of a partner—the FOS allows clinicians to ascertain whether anorgasmia is generalized, situational, or simply a normative reflection of a lack of direct clitoral engagement. Furthermore, by providing an explicit “Does not apply to me” response alternative, the instrument prevents the misclassification of sexual behavioral non-engagement as functional orgasmic failure.

In research contexts, the FOS provides sexologists, epidemiologists, and relationship scientists with a nuanced instrument capable of assessing interventions aimed at closing the documented “orgasm gap”—the pervasive discrepancy between men and women in orgasmic frequency during heterosexual encounters. The scale enables researchers to assess how varying relational dynamics, sexual communication patterns, sexual scripts, and partner behaviors directly influence orgasmic consistency across each specific anatomical pathway. Furthermore, by evaluating satisfaction with both orgasm number and quality independently from behavioral frequency, the FOS facilitates the exploration of complex psychological phenomena, such as women who experience low orgasmic consistency yet report high sexual satisfaction, or conversely, women who climax regularly but experience low subjective orgasmic quality.

5. Psychological Construct

The Female Orgasm Scale operationalizes female orgasmic functioning not as a monolithic, binary physiological reflex, but as a multidimensional construct characterized by behavioral variability, anatomical specificity, and cognitive-affective appraisal. The instrument captures two empirically and conceptually distinct dimensions, alongside an independent coital marker:

Orgasm from Clitoral Stimulation Subscale (Items 2–5)

This subscale measures the consistency with which a woman experiences orgasm during sexual interactions involving intentional, direct stimulation of the external clitoral glans and hood. Modern neuroanatomical research demonstrates that the clitoris is an extensive anatomical complex—the clitoral-urethral-vaginal (CUV) complex—possessing thousands of sensory nerve endings that converge onto the pudendal nerve. The FOS isolates four behavioral modalities through which clitoral engagement occurs during partnered sex:

• Coitus with Simultaneous Direct Clitoral Stimulation (Item 2): Quantifies orgasmic consistency when penile-vaginal penetration is paired with concurrent direct manual or mechanical stimulation of the clitoris. This behavioral configuration bridges vaginal containment with direct external sensory input.
• Partner-Administered Manual Stimulation (Item 3): Assesses the percentage of time orgasm occurs when the partner directly stimulates the genitals and clitoris using their hands or fingers. This behavior reflects partner manual dexterity, responsiveness to real-time feedback, and intimate tactile communication.
• Partnered Self-Stimulation (Item 4): Evaluates orgasmic consistency when the woman herself manually or mechanically manipulates her own clitoris in the physical presence of her partner. This item captures sexual agency, self-directed erotic autonomy, and comfort with sexual display, often serving as a critical therapeutic marker in overcoming sexual inhibition.
• Partner-Administered Oral Stimulation (Item 5): Measures orgasmic frequency resulting from cunnilingus. Oral sex often provides sustained, rhythmic, and highly focused clitoral stimulation with minimal pelvic friction, frequently representing one of the most reliable modalities for partnered female orgasm.

Satisfaction with Orgasm Subscale (Items 6–7)

This affective-cognitive dimension recognizes that physical orgasmic occurrence does not automatically correspond to psychological gratification. A woman may experience orgasms that feel emotionally disconnected, rushed, or physically underwhelming, or she may experience infrequent orgasms that are deeply fulfilling. This subscale disaggregates satisfaction into two evaluative components:

• Satisfaction with Orgasm Quantity/Number (Item 6): Assesses subjective contentment with the numeric frequency of orgasms experienced during partnered encounters. This evaluates whether a woman feels her quantitative sexual appetite and physiological capacity are adequately met.
• Satisfaction with Orgasm Quality and Experience (Item 7): Evaluates the qualitative, sensory, and emotional depth of the orgasms achieved. This construct taps into subjective intensity, duration, whole-body involvement, emotional intimacy, and post-orgasmic resolution.

Coitus-Dependent Orgasm Consistency (Item 1)

Item 1 measures the percentage of time a woman reaches orgasm through vaginal penetration only, without any concurrent direct clitoral stimulation. Within psychometric factor analyses, Item 1 demonstrated weak or divergent loading patterns relative to Items 2–5, confirming theoretical assertions that orgasm derived exclusively from penile thrusting operates through distinct physiological and sensory pathways (e.g., indirect traction of the labia minora pulling the clitoral prepuce, pressure against the internal clitoral crura or bulbs, or stimulation of the anterior vaginal wall) compared to direct external clitoral manipulation. Retaining Item 1 as an independent marker provides critical diagnostic clarity regarding coital orgasmic capacity without confounding the clitoral subscale.

6. Theoretical Framework

The Female Orgasm Scale is grounded in modern sexological theories of female sexual response, feminist psychophysiological models, and cognitive-behavioral paradigms of sexual function.

The Dual Control Model of Sexual Response

Conceptualized by John Bancroft and Erick Janssen at the Kinsey Institute, the Dual Control Model posits that sexual arousal and orgasmic attainment represent a homeostatic balance between neurobiological sexual excitation (SE) and sexual inhibition (SI). While physiological stimulation provides the excitatory afferent signals necessary to approach the orgasmic threshold, contextual, psychological, or relational threats activate inhibitory mechanisms. The FOS reflects this balance by assessing distinct sexual activities that vary inherently in their cognitive and emotional vulnerability. For example, partnered self-stimulation (Item 4) often requires significant downregulation of sexual inhibition (e.g., freedom from body shame or performance anxiety) compared to passive reception of oral stimulation (Item 5).

The Circular and Responsive Model of Female Sexual Response

Traditional linear models of human sexual response—such as those articulated by Masters and Johnson and refined by Helen Singer Kaplan (Desire → Arousal → Plateau → Orgasm → Resolution)—have been heavily critiqued for failing to capture the complexity of female sexual desire. Rosemary Basson proposed an alternative circular model emphasizing that female sexual motivation is often responsive rather than spontaneous, driven by emotional intimacy, relational closeness, and psychological receptivity. In Basson’s model, the physical experience of orgasm feeds directly back into emotional intimacy, which subsequently shapes future sexual motivation. The FOS aligns directly with this framework by including an explicit Satisfaction with Orgasm dimension. Subjective satisfaction serves as the cognitive appraisals mechanism that determines whether sexual encounters reinforce sexual well-being or foster sexual avoidance.

Anatomical De-centering of the Coital Imperative

The FOS is deeply informed by modern feminist and anatomical reassessments of female sexuality (e.g., the anatomical mappings of the human clitoris by Helen O’Connell and colleagues). For over a century, psychodynamic frameworks stemming from Sigmund Freud posited that the transition from a “clitoral” orgasm to a “vaginal” orgasm represented psychosexual maturity. Subsequent physiological investigations conclusively refuted this dichotomy, demonstrating that all female orgasms share a common neurovascular substrate rooted in the clitoral network. However, a cultural “coital imperative”—the persistent belief that heterosexual intercourse is incomplete without simultaneous penile-vaginal climax—continues to generate distress among women who require direct clitoral manipulation. The FOS operationalizes this theoretical reframing by validating clitoral stimulation across diverse behavioral repertoires, demonstrating that orgasmic variation across modalities is an expected anatomical reality rather than an individual pathology.

7. Validity

The construct, convergent, discriminant, and content validity of the Female Orgasm Scale were established across a series of three iterative scale-development investigations conducted by McIntyre-Smith and Fisher with female undergraduate cohorts (total combined N = 651).

Content and Face Validity

Content validity was established through systematic item generation based on contemporary sexological literature, clinical taxonomies of sexual dysfunction, and psychometric scaling standards (Netemeyer, Bearden, & Sharma, 2003; Streiner & Norman, 2008). Items were designed to cover the full spectrum of partnered sexual behaviors that lead to female orgasm. The inclusion of an explicit “Does not apply to me” option was a pivotal structural innovation ensuring content validity, preventing respondents who abstain from specific behaviors (e.g., cunnilingus or partnered masturbation) from having their scores conflated with individuals who engage in those behaviors but fail to climax.

Convergent Validity

Convergent validity was evaluated by correlating FOS scores with established measures of female sexual functioning, primarily the Female Sexual Function Index (FSFI; Rosen et al., 2000). The total FOS score demonstrated a strong, statistically significant positive correlation with the FSFI Orgasm subscale (r = .71, p < .001). This large effect size confirms that the FOS accurately captures core orgasmic capacity while offering greater behavioral disaggregation. The FOS also demonstrated moderate, significant correlations with the overall FSFI total score and its remaining subscales (arousal, lubrication, satisfaction, and pain), with coefficients ranging from r = .20 to .55 (p < .01). Notably, the FOS was not significantly correlated with the FSFI Sexual Desire subscale, consistent with theoretical frameworks indicating that orgasmic capacity and subjective sexual drive operate as distinct sexual dimensions.

Furthermore, convergent validity for the affective dimension was established by comparing the FOS Satisfaction with Orgasm subscale with the FSFI Satisfaction subscale. The resulting positive correlation (r = .31, p < .01) confirmed that the FOS captures relevant relational and personal satisfaction variance while focusing specifically on orgasmic appraisal.

Discriminant Validity

Discriminant validity was established by evaluating the FOS against measures of unrelated psychological constructs and response biases:

• Social Desirability: To ensure that self-reported orgasmic frequency was not contaminated by impression management or need for social approval, the FOS was administered alongside the Marlowe-Crowne Social Desirability Scale (MCSD) (Crowne & Marlowe, 1964). Correlations between the MCSD and the FOS total score, subscales, and individual items were non-significant and near zero, demonstrating that the scale is free from social desirability bias.
• General Psychological Distress: The scale was evaluated against the Depression Anxiety Stress Scales (DASS-21; Henry & Crawford, 2005). The FOS total score and subscales demonstrated no significant correlations with generalized depressive or anxiety symptoms, confirming that the scale assesses specific sexual functionality rather than diffuse negative affectivity.

8. Reliability

The Female Orgasm Scale exhibits strong internal consistency, item homogeneity, and temporal stability across repeated psychometric assessments.

Internal Consistency

Across the three developmental studies (Study 1: N = 198; Study 2: N = 242; Study 3: N = 211), the total FOS consistently exhibited high Cronbach’s alpha coefficients, ranging from α = .84 to α = .86. Subscale reliability analyses revealed consistent stability:

• Orgasm from Clitoral Stimulation (Items 2–5): Cronbach’s α ranged from .81 to .82 across samples, demonstrating high reliability for assessing clitorally mediated orgasmic consistency.
• Satisfaction with Orgasm (Items 6–7): Cronbach’s α ranged from .72 to .90 across samples, indicating strong internal consistency for the two-item affective appraisal dimension.

Item-Total and Inter-Item Correlations

Corrected item-total correlations for the comprehensive scale ranged from r = .41 to .77, substantially exceeding the recommended psychometric threshold of .30 (Streiner & Norman, 2008). Within the respective subscales, corrected item-total correlations were higher, ranging from r = .56 to .81, confirming that each item contributes meaningfully to its assigned construct. Inter-item correlations for the total scale ranged from r = .19 to .61, reflecting acceptable breadth without excessive redundancy, while inter-item correlations within the two distinct subscales clustered between r = .43 and .68.

Test-Retest Reliability

Temporal stability was evaluated in Study 3 over a 4-week interval among a sub-sample of sexually active female undergraduates. The 4-week test-retest reliability coefficient for the total FOS score was excellent (r = .82, p < .001). Subscale test-retest reliability was similarly stable, with coefficients ranging from r = .62 to .78 (p < .001). These findings indicate that while orgasmic experience fluctuates naturally across distinct partnered encounters, an individual’s contextual consistency and subjective satisfaction remain stable over intermediate temporal spans.

9. Factor Analysis

The factor structure of the Female Orgasm Scale was derived through an iterative exploratory factor analysis (EFA) framework across three successive validation samples, conforming to rigorous psychometric scale-development standards (Netemeyer et al., 2003).

Iterative Development Stages

1. Study 1 (Item Generation and Initial Pruning): An initial pool of 17 candidate items was administered to 198 heterosexually active female undergraduates. Item analyses and EFAs identified significant psychometric limitations in 9 items, including severe range restriction (e.g., >50% endorsement of a single category), low communalities (< .30), weak corrected item-total correlations (r < .30), and conceptual redundancy. These 9 items were excised, and 5 new items were drafted to better capture underrepresented stimulation contexts, yielding a 13-item instrument.
2. Study 2 (Factor Refinement): The revised 13-item scale was administered to a second cohort of 242 female undergraduates. Subsequent factor analyses and item-reduction strategies eliminated 6 additional items that demonstrated cross-loadings (> .35 on non-target factors) or poor communalities. Two replacement items focusing on subjective satisfaction were constructed to address affective evaluation, producing a 9-item scale.
3. Study 3 (Final Psychometric Confirmation): The 9-item scale was administered to 211 female undergraduates. Psychometric analyses indicated that two items exhibited suboptimal inter-item correlations and psychometric redundancy. These items were deleted, resulting in the final, highly cohesive 7-item Female Orgasm Scale.

Latent Structure and Factor Loadings

Principal axis factoring and principal component analyses with oblique rotations (reflecting the theoretical expectation that orgasmic frequency and orgasmic satisfaction are correlated) consistently isolated two primary latent dimensions:

• Factor 1: Orgasm from Clitoral Stimulation: Comprising Items 2, 3, 4, and 5. Factor loadings for these items clustered robustly between .65 and .88, with communalities exceeding .45. These items reflect orgasmic consistency across diverse manifestations of direct clitoral manipulation.
• Factor 2: Satisfaction with Orgasm: Comprising Items 6 and 7. Factor loadings for these items exceeded .80, with strong communalities, indexing cognitive-affective satisfaction with frequency and experiential quality.

Item 1 Status: Item 1 (vaginal penetration without clitoral stimulation) exhibited a distinct psychometric profile, characterized by lower factor loadings onto the primary Clitoral Stimulation factor and low-to-moderate communality. Rather than forcing Item 1 into the clitoral dimension or discarding it, the authors preserved Item 1 as an independent index. This psychometric separation empirically validates clinical observations that unassisted coital orgasmic consistency operates independently from clitorally driven orgasmic capacity.

10. Instrument / Measurement Tool

The Female Orgasm Scale is a self-administered questionnaire formatted for either paper-and-pencil or secure digital completion. It requires approximately 2 to 5 minutes to complete.

Test Structure

• Item Count: 7 items total.
• Behavioral Frequency Domain (Items 1–5): Evaluates the percentage of time orgasm occurs across five distinct partnered sexual behaviors:
  • Item 1: Vaginal penetration only (no direct clitoral stimulation).
  • Item 2: Vaginal penetration with simultaneous direct clitoral stimulation.
  • Item 3: Partner manual stimulation of the clitoris/genitals.
  • Item 4: Self-stimulation of the clitoris/genitals in the presence of a partner.
  • Item 5: Partner oral stimulation of the clitoris/genitals.
• Subjective Satisfaction Domain (Items 6–7): Evaluates cognitive-affective contentment:
  • Item 6: Satisfaction with the number (frequency) of orgasms.
  • Item 7: Satisfaction with the quality or subjective experience of orgasms.

Response Scales

• Items 1–5: 11-point percentage scale in 10% increments: 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%. Each item also includes a distinct categorical escape option: Does not apply to me (with clarifying behavioral text).
• Items 6–7: 7-point Likert satisfaction scale: Very Satisfied (7), Moderately Satisfied (6), Slightly Satisfied (5), Neither Satisfied nor Unsatisfied (4), Slightly Unsatisfied (3), Moderately Unsatisfied (2), Very Unsatisfied (1).

Scoring Guidelines and Weighting Algorithm

Because Items 1–5 utilize an 11-point metric (scored 0–10) while Items 6–7 utilize a 7-point metric (scored 1–7), the authors established a differential weighting protocol to align the subscales for total score aggregation:

1. Handling “Does Not Apply to Me”: Researchers must determine a priori whether non-applicable responses are coded as missing data or imputed as 0. In clinical diagnostic paradigms assessing generalized function, coding non-engagement as missing data is recommended to prevent deflating orgasmic consistency across behaviors the respondent simply does not practice.
2. Raw Item Scoring:
   • Items 1–5 are scored: 0% = 0, 10% = 1, 20% = 2, 30% = 3, 40% = 4, 50% = 5, 60% = 6, 70% = 7, 80% = 8, 90% = 9, 100% = 10.
   • Items 6–7 are scored: Very Unsatisfied = 1, Moderately Unsatisfied = 2, Slightly Unsatisfied = 3, Neither Satisfied nor Unsatisfied = 4, Slightly Satisfied = 5, Moderately Satisfied = 6, Very Satisfied = 7.
3. Item Weighting:
   • Multiply the raw scores of Items 1–5 by 7 (yields a potential range of 0 to 70 per item).
   • Multiply the raw scores of Items 6–7 by 10 (yields a potential range of 10 to 70 per item).
4. Composite Scores:
   • Total FOS Score: Sum the weighted scores across all 7 items (range: 20 to 490), or calculate the mean weighted item score. Higher scores reflect greater overall orgasmic consistency and satisfaction.
   • Orgasm from Clitoral Stimulation Subscale: Sum or average the raw scores of Items 2–5 (unweighted, raw range 0–40). Weighting is unnecessary when evaluating subscales in isolation due to uniform metric scaling within items.
   • Satisfaction with Orgasm Subscale: Sum or average the raw scores of Items 6–7 (unweighted, raw range 2–14).
   • Coital Orgasm Marker: Examine Item 1 raw score independently (range 0–10).

11. Permissions & Fee and Test Year

The Female Orgasm Scale was developed and validated in the late 2000s and formally published in sexological compendia and peer-reviewed psychometric literature by Alexandra McIntyre-Smith and William A. Fisher. The instrument is considered open-access for non-commercial academic, scientific research, and educational applications. Researchers and licensed clinicians are permitted to utilize the scale provided appropriate scholarly citation is credited to the original authors.

For commercial implementations, clinical trials funded by commercial entities, or inclusion in proprietary digital health applications, users should direct formal copyright and licensing inquiries to the scale authors (Dr. William A. Fisher at [email protected] or Dr. Alexandra McIntyre-Smith at [email protected]) via the Department of Psychology at The University of Western Ontario, London, Ontario, Canada.

12. References

• Bancroft, J., & Janssen, E. (2000). The dual control model of male sexual response: A theoretical approach to centrally mediated erectile dysfunction. European Urology, 38(3), 257–275. https://doi.org/10.1159/000020296
• Basson, R. (2000). The female sexual response: A different model. Journal of Sex & Marital Therapy, 26(1), 51–65. https://doi.org/10.1080/009262300278641
• Crowne, D. P., & Marlowe, D. (1964). The approval motive: Studies in evaluative dependence. John Wiley & Sons.
• Henry, J. D., & Crawford, J. R. (2005). The short-form version of the Depression Anxiety Stress Scales (DASS-21): Construct validity and normative data in a large non-clinical sample. British Journal of Clinical Psychology, 44(2), 227–239. https://doi.org/10.1348/014466505X29657
• Kaplan, H. S. (1979). Disorders of sexual desire and other new concepts and techniques in sex therapy. Brunner/Mazel.
• Masters, W. H., & Johnson, V. E. (1966). Human sexual response. Little, Brown and Company.
• McIntyre-Smith, A., & Fisher, W. A. (2011). Female Orgasm Scale (FOS). In T. D. Fisher, C. M. Davis, W. L. Yarber, & S. L. Davis (Eds.), Handbook of Sexuality-Related Measures (3rd ed., pp. 320–322). Routledge.
• Netemeyer, R. G., Bearden, W. O., & Sharma, S. (2003). Scaling procedures: Issues and applications. Sage Publications. https://doi.org/10.4135/9781412985772
• O’Connell, H. E., Sanjeevan, K. V., & Hutson, J. M. (2005). Anatomy of the clitoris. The Journal of Urology, 174(4), 1189–1195. https://doi.org/10.1097/01.ju.0000173639.38898.cd
• Rosen, R., Brown, C., Heiman, J., Leiblum, S., Meston, C., Shabsigh, R., Ferguson, D., & D’Agostino, R. (2000). The Female Sexual Function Index (FSFI): A multidimensional self-report instrument for the assessment of female sexual function. Journal of Sex & Marital Therapy, 26(2), 191–208. https://doi.org/10.1080/009262300278597
• Streiner, D. L., & Norman, G. R. (2008). Health measurement scales: A practical guide to their development and use (4th ed.). Oxford University Press. https://doi.org/10.1093/acprof:oso/9780199231881.001.0001

13. Items of the Scale (Questionnaire)