Perceived Health Competence Scale (PHCS)

Abstract

The Perceived Health Competence Scale (PHCS) is an 8-item psychometric instrument developed by M. Susan Smith, Kenneth A. Wallston, and Craig A. Smith in 1995 to assess an individual’s generalized sense of personal competence in managing their personal health. Rooted within social cognitive theory and health psychology, the PHCS integrates both efficacy expectations (the belief in one’s capacity to execute health-promoting behaviors) and outcome expectations (the belief that executing those behaviors will lead to favorable health outcomes) into a unified, domain-specific construct. The scale uses a 6-point Likert response format ranging from 1 (Strongly Disagree) to 6 (Strongly Agree), featuring a balanced composition of four positively keyed items and four negatively keyed (reverse-scored) items. Psychometric evaluations across diverse community, clinical, and demographic samples have consistently demonstrated robust internal consistency reliability, with Cronbach’s alpha coefficients typically ranging from .82 to .91, and solid test-retest reliability across multi-week intervals ranging from .70 to .83. Factor analytic investigations have established that despite secondary variance attributable to reverse-wording method effects, the PHCS measures a largely unidimensional overarching construct of health competence. The scale possesses well-documented convergent validity through moderate to high correlations with the Internal Health Locus of Control subscale, Generalized Self-Efficacy, positive affect, and health-related quality of life measures, while exhibiting discriminant validity against chance locus of control, powerful others locus of control, and impression management. Demonstrating high predictive utility across preventive behaviors, chronic illness self-management, medical regimen adherence, and functional recovery, the PHCS remains one of the most widely utilized and validated brief instruments in behavioral medicine and public health research.

Keywords

Perceived Health Competence Scale, PHCS, health self-efficacy, health locus of control, behavioral medicine, chronic illness management, social cognitive theory, patient-reported outcome measures, psychometrics, preventive health behavior, outcome expectancy, self-regulation.

Authors

The Perceived Health Competence Scale was conceptualized, operationalized, and psychometrically validated by a collaborative team of behavioral scientists and health psychologists based at Vanderbilt University in Nashville, Tennessee, USA:

• M. Susan Smith, Ph.D. — Department of Psychology and Human Development, Peabody College, Vanderbilt University. Dr. Smith’s research focused on health-related cognition, developmental health behaviors, and psychometric operationalization of perceived control.
• Kenneth A. Wallston, Ph.D. (1942–2021) — Professor of Psychology in Nursing at Vanderbilt University School of Nursing. A pioneering figure in health psychology and behavioral medicine, Dr. Wallston is internationally renowned for creating the Multidimensional Health Locus of Control (MHLC) Scales and authoring foundational research on perceived control, adherence, and empowerment in chronic illness.
• Craig A. Smith, Ph.D. — Department of Psychology and Human Development, Peabody College, Vanderbilt University. Dr. Smith is a recognized authority on cognitive appraisal theories of emotion, psychological stress, and the interaction between self-efficacy and coping processes.

Purpose

The primary purpose of the Perceived Health Competence Scale (PHCS) is to provide health researchers, epidemiologists, and behavioral clinicians with a brief, psychometrically sound, domain-specific measure of an individual’s perceived capability to navigate health challenges and achieve desired health outcomes. Prior to the development of the PHCS, health psychology relied heavily either on generalized self-efficacy scales—such as the Generalized Self-Efficacy Scale developed by Ralf Schwarzer and Matthias Jerusalem—or on locus of control frameworks, particularly Wallston’s Multidimensional Health Locus of Control (MHLC) scales.

Although generalized self-efficacy measures capture broad motivational traits, they frequently lack predictive granularity when applied to idiosyncratic health behaviors such as smoking cessation, dietary restriction, insulin titration, or medical regimen adherence. Conversely, locus of control measures primarily index beliefs regarding who or what governs health outcomes (e.g., internal agency, powerful medical personnel, or chance/fate), without capturing whether the individual believes they possess the actual behavioral skills, emotional fortitude, and cognitive resources necessary to produce those outcomes. The PHCS was constructed specifically to bridge this empirical and conceptual gap.

In clinical and health promotion settings, the PHCS serves several diagnostic and evaluative functions:

• Baseline Assessment of Health Self-Regulation: Clinicians utilize the PHCS to identify patients who feel powerless or ineffective in dealing with diagnosis-related changes, enabling tailored psychoeducational interventions before introducing complex self-care regimens.
• Treatment Adherence and Outcome Prediction: Higher baseline PHCS scores systematically predict superior adherence to medication protocols, exercise rehabilitation in cardiac populations, glycemic control in type 1 and type 2 diabetes mellitus, and attendance at follow-up clinical appointments.
• Evaluation of Health Interventions: The scale functions as a sensitive outcome indicator in behavioral health trials, capturing shifts in patients’ confidence and perceived mastery following cognitive-behavioral therapy (CBT), disease self-management programs (e.g., the Stanford Chronic Disease Self-Management Program), and lifestyle modification workshops.
• Epidemiological and Gerontological Research: In older adult cohorts, perceived health competence plays a protective role against psychological distress in the face of multi-morbidity, serving as a psychological buffer that moderates the impact of functional decline on depression and quality of life.

Psychological Construct

The psychological construct evaluated by the PHCS is perceived health competence, defined as a generalized, domain-specific expectancy encompassing both self-efficacy and outcome expectancies related to one’s health status. To comprehend the nuances of this construct, it must be dissected into its dual theoretical dimensions: health-related self-efficacy expectations and health-related outcome expectations.

1. Health Efficacy Expectations

Efficacy expectations refer to individuals’ subjective confidence that they can successfully execute the behaviors and action plans required to manage their health. Within the PHCS, this dimension is represented by items assessing personal capability and agency, such as “I handle myself well with respect to my health” (Item 1) and “I am able to do things for my health as well as most other people” (Item 8). When individuals possess high efficacy expectations, they view health-related challenges—such as initiating a strenuous rehabilitation program or reorganizing nutritional habits—as manageable tasks rather than insurmountable barriers. They exhibit higher resilience against relapses, deploy more proactive problem-solving strategies, and demonstrate lower vulnerability to health-related anxiety.

2. Health Outcome Expectations

Outcome expectations involve the subjective belief that engaging in specific health-directed actions will lead to the anticipated physical or psychological improvements. Even if a person feels entirely capable of following a medical regimen, they will not sustain motivation if they believe that the trajectory of their health is governed by irreversible biological decline or predetermined misfortune. The PHCS captures these outcome contingencies through negatively worded items measuring frustration and perceived futility, such as “No matter how hard I try, my health just doesn’t turn out the way I would like” (Item 2) and “Typically, my plans for my health don’t work out well” (Item 7).

Construct Differentiation

Perceived health competence occupies an intermediate level of specificity within the hierarchy of psychological control constructs:

• Versus Generalized Self-Efficacy: Generalized self-efficacy represents a global trait reflecting broad competence across life challenges. A CEO might exhibit exceptionally high generalized self-efficacy in professional negotiations, yet manifest low perceived health competence when diagnosed with hypertension or osteoarthritis. The PHCS narrows the frame of reference specifically to the somatic, biological, and medical domains of existence.
• Versus Task-Specific Health Self-Efficacy: Task-specific measures evaluate discrete behaviors (e.g., confidence in using an inhaler during an asthma attack or resisting sweets during a social dinner). Although highly predictive of that specific behavior, task-specific scales cannot capture an individual’s broad, overarching orientation toward their biological health. The PHCS operates at an intermediate level: general enough to predict broad health maintenance, yet specific enough to retain clinical predictive power across various conditions.
• Versus Internal Health Locus of Control: While internal locus of control establishes that causation rests within oneself (e.g., “My own behavior determines how quickly I recover”), it does not ensure perceived competence (e.g., “I know it is my responsibility, but I am totally unable to do it”). Perceived health competence explicitly incorporates the self-appraisal of mastery, bridging the gap between causal attribution and behavioral activation.

Theoretical Framework

The Perceived Health Competence Scale is embedded primarily within Albert Bandura’s Social Cognitive Theory (1977, 1986, 1997) and Julian Rotter’s Social Learning Theory (1954, 1966), while incorporating elements of Richard Lazarus and Susan Folkman’s (1984) Cognitive Appraisal Theory of Stress and Coping.

Bandura’s Social Cognitive Theory

Bandura postulated that human agency operates within a reciprocal triadic model wherein cognitive factors, environmental influences, and behaviors interact dynamically. Central to this formulation is the conceptual separation of efficacy expectations (the belief in one’s behavioral mastery) from outcome expectancies (the belief that behavior produces a designated outcome). Bandura argued that the coexistence of high self-efficacy and positive outcome expectations generates productive action and psychological engagement. Conversely, high self-efficacy paired with negative outcome expectations produces despondency and cynicism, while low self-efficacy paired with positive outcome expectations generates self-devaluation and anxiety.

Smith, Wallston, and Smith (1995) designed the PHCS specifically on the premise that an individual’s subjective sense of competence in health management represents a combined distillation of these two cognitive vectors within the health sphere. When health self-efficacy and health outcome expectations are combined, they produce an overarching mental model of subjective health mastery.

Rotter’s Social Learning Theory

Julian Rotter’s work posited that the potential for a given behavior to occur in a specific situation is a function of the expectancy that the behavior will yield a reinforcement, multiplied by the psychological value of that reinforcement. Rotter conceptualized Generalized Expectancies—generalized cognitive beliefs formed through cumulative learning histories across diverse situations. In constructing the PHCS, the authors treated perceived health competence as a domain-specific generalized expectancy: a cognitive appraisal rooted in a person’s cumulative history of medical encounters, illness management, bodily symptom processing, and lifestyle interventions.

Lazarus and Folkman’s Cognitive Appraisal Model

From the perspective of stress and coping theory, health stressors (e.g., receiving a diagnosis, experiencing chronic pain, facing physical limitations) trigger a two-stage appraisal process: primary appraisal (evaluating the threat or harm) and secondary appraisal (evaluating available coping resources and personal options). Perceived health competence acts as a critical secondary appraisal resource. Individuals with elevated PHCS scores evaluate health problems not as irremediable catastrophes, but as challenges for which viable behavioral and cognitive solutions can be devised (Item 3: “It is difficult for me to find effective solutions to the health problems that come my way”—reverse-scored).

Validity

The psychometric validity of the PHCS has been extensively documented in behavioral medicine literature across diverse healthy, community-dwelling, and clinical populations.

Construct and Convergent Validity

In their initial validation series across four independent studies involving university students, community adults, and clinical cohorts, Smith et al. (1995) demonstrated strong convergent validity:

• Internal Health Locus of Control: PHCS scores demonstrated statistically significant positive correlations with the Internal subscale of the Multidimensional Health Locus of Control (MHLC) scale ($r = .40$ to $.56, p < .001$), confirming that perceived health competence aligns with the belief that health outcomes are shaped by one's personal actions.
• General Self-Efficacy: PHCS scores correlated moderately with the Generalized Self-Efficacy Scale ($r = .38$ to $.48, p < .001$), indicating shared variance as a competence belief while confirming that domain-specific health variance remains distinct from general self-assurance.
• Self-Rated Health: Moderate positive associations were documented between PHCS and global self-rated health ($r = .41$ to $.52$), demonstrating that individuals who view themselves as competent in health matters perceive their physiological health status more favorably.
• Optimism and Affect: The PHCS displayed significant positive correlations with dispositional optimism measured via the Life Orientation Test (LOT) ($r = .35$ to $.45$) and negative correlations with depressive symptoms measured via the Center for Epidemiologic Studies Depression Scale (CES-D) ($r = -.32$ to $-.47$).

Discriminant Validity

Smith et al. (1995) and subsequent independent researchers demonstrated that perceived health competence is empirically separable from external control constructs and response biases:

• Chance Health Locus of Control: PHCS exhibited significant negative correlations with the Chance subscale of the MHLC ($r = -.31$ to $-.48, p < .001$), demonstrating that high perceived competence directly rejects the assumption that health status is merely an arbitrary product of luck or fate.
• Powerful Others Health Locus of Control: Correlations between the PHCS and the Powerful Others subscale were uniformly low to negligible ($r = -.08$ to $.12$, non-significant in most samples), establishing that health competence does not require reliance upon or rejection of medical professionals, but functions as an autonomous construct.
• Social Desirability: Correlations between the PHCS and the Marlowe-Crowne Social Desirability Scale were minimal ($r = .10$ to $.16$), verifying that scores reflect genuine self-referent beliefs rather than an attempt to present an idealized self-image.

Criterion and Predictive Validity

Numerous longitudinal and cross-sectional studies have established the predictive power of the PHCS across varied health domains:

• Gerontological Health Behaviors: Marks and Lutgendorf (1999) investigated older adults ($N = 144$, mean age 73.1 years) to evaluate whether PHCS predicted health maintenance behaviors above and beyond the Big Five personality traits (Neuroticism, Extraversion, Openness, Agreeableness, Conscientiousness). Hierarchical regression analyses revealed that PHCS contributed unique, significant variance in predicting physical activity, dietary compliance, and preventive health practices after controlling for personality factors.
• Primary Care Settings: In an extensive validation study within a UK primary care context, Dempster and Donnelly (2008) administered the PHCS to 433 patients attending general practice clinics. PHCS scores significantly differentiated patients according to their functional capacity, psychological distress (measured by the GHQ-12), and chronic disease burden.
• Chronic Disease Management: Studies in type 2 diabetes mellitus demonstrate that higher PHCS scores correlate with lower glycosylated hemoglobin ($HbA_{1c}$) levels, mediated through increased frequency of blood glucose self-monitoring and physical exercise. Similarly, in cardiovascular rehabilitation programs, baseline PHCS independently predicts program completion and long-term functional recovery.

Reliability

The reliability of the Perceived Health Competence Scale has been rigorously evaluated using classical test theory metrics, consistently exceeding acceptable psychometric benchmarks across both research and clinical implementations.

Internal Consistency Reliability

Across the four original validation samples conducted by Smith et al. (1995):

• Sample 1 (College Undergraduates, $N = 345$): Cronbach’s alpha coefficient was $\alpha = .84$.
• Sample 2 (Community Adults, $N = 250$): Cronbach’s alpha coefficient was $\alpha = .87$.
• Sample 3 (Adults with Chronic Illness, $N = 188$): Cronbach’s alpha coefficient was $\alpha = .88$.
• Sample 4 (Older Adults, $N = 162$): Cronbach’s alpha coefficient was $\alpha = .90$.

Independent cross-validation studies have corroborated these indices. For instance, Marks and Lutgendorf (1999) reported an alpha of $.86$ in an independent older adult sample, while Dempster and Donnelly (2008) documented an alpha of $.84$ among primary care attendees in the United Kingdom. Across translations into languages such as Chinese, German, Turkish, and Spanish, Cronbach’s alpha values typically span $.82$ to $.91$, well above the $.70$ standard for research tools and approaching the $.90$ threshold recommended for individual clinical decision-making.

Item-Total Correlations

Corrected item-total correlations across validation studies demonstrate consistent homogeneity across the instrument. Across published investigations, corrected item-total correlations for each of the eight items regularly range from $.50$ to $.76$, with no single item’s deletion leading to an increase in overall internal consistency.

Test-Retest Reliability and Temporal Stability

The temporal stability of the PHCS reflects its theoretical definition as an open, modifiable generalized expectancy rather than an immutable personality trait:

• Two- to Four-Week Intervals: In initial undergraduate cohorts assessed across a 3-week test-retest period, the stability coefficient was $r_{tt} = .83 (p < .001)$, indicating strong short-term stability in the absence of acute health interventions.
• Longer-Term Stability (Six to Twelve Months): In prospective health tracking studies with older adults over a 6-month interval, test-retest correlations remained robust at $r_{tt} = .70$ to $.74$, confirming that the PHCS reflects a stable cognitive baseline while remaining sensitive to systemic medical life events, major diagnoses, or behavioral interventions.

Factor Analysis

The latent structural architecture of the PHCS has been a focus of psychometric inquiry, centering on whether the instrument functions as a strictly unidimensional scale or exhibits a two-factor structure driven by substantive constructs or method variance.

Exploratory Factor Analysis (EFA)

In the original EFA conducted by Smith, Wallston, and Smith (1995) using principal axis factoring with oblique rotation, the 8 items yielded an initial two-factor extraction with eigenvalues greater than 1.0. These two factors accounted for over 60% of the common variance:

• Factor 1: Comprised the four negatively worded, reverse-scored items (Items 2, 3, 6, and 7), loading between $.68$ and $.84$. These items capture perceived ineffectiveness and outcome frustration.
• Factor 2: Comprised the four positively worded items (Items 1, 4, 5, and 8), loading between $.65$ and $.81$. These items capture perceived self-mastery and goal accomplishment.

Crucially, the correlation between these two extracted factors was substantial ($r = -.52$ to $-.64$ across samples). Because of the strong conceptual overlap and high inter-factor correlation, Smith et al. argued that the bifactorial emergence represented a methodological artifact common in balanced scales (i.e., positive vs. negative item polarity) rather than two substantively divergent psychological traits. Consequently, they recommended utilizing the instrument as a single composite index of perceived health competence.

Confirmatory Factor Analysis (CFA)

Subsequent psychometric investigations have applied Confirmatory Factor Analysis (CFA) to evaluate competing measurement models:

1. Strict One-Factor Model: Constraining all 8 items to load onto a single general health competence latent factor typically produces modest to marginal model fit indices (e.g., $\chi^2/df > 4.5$, $\text{CFI} \approx .88-.91$, $\text{RMSEA} \approx .09-.11$), driven by correlated residual variance among the reverse-scored items.
2. Correlated Two-Factor Model: Allowing positively phrased items (efficacy) and negatively phrased items (ineffectiveness) to load onto two correlated latent factors yields superior fit indices ($chi^2/df < 2.5$,$text{CFI} > .96$,$text{TLI} > .95$,$text{RMSEA} < .06$).
3. Bifactor Model / Single Substantive Factor with Method Factor: Dempster and Donnelly (2008) formally evaluated whether the two-factor solution represented substantive multidimensionality or a wording effect. Their CFA demonstrated that a model positing one general substantive factor of Perceived Health Competence alongside an orthogonal method factor for the negatively keyed items provided the optimal fit to the empirical data ($\chi^2/df = 1.82$, $\text{CFI} = .98$, $\text{RMSEA} = .044$).

Because the general substantive factor accounts for the vast majority of the common variance across items, psychometric consensus supports summing or averaging all 8 items to produce a unified Perceived Health Competence composite score, while recognizing that reverse-coded items introduce minor method-specific variance.

Instrument / Measurement Tool

The operational characteristics and administrative guidelines for the Perceived Health Competence Scale are outlined below:

• Instrument Name: Perceived Health Competence Scale (PHCS)
• Alternative Titles: Smith-Wallston Perceived Health Competence Scale
• Primary Reference: Smith, M. S., Wallston, K. A., & Smith, C. A. (1995)
• Format / Administration: Self-administered paper-and-pencil questionnaire, digital web-based survey, or structured clinical interview.
• Target Population: Adolescents and adults across the lifespan (ages 16–90+ years), applicable in general, community, outpatient, and chronic medical inpatient populations.
• Completion Time: Approximately 2 to 3 minutes.
• Item Count: 8 items.
• Item Composition:
  • 4 positively worded items (Items 1, 4, 5, 8)
  • 4 negatively worded items (Items 2, 3, 6, 7)
• Response Scale: 6-point Likert-type scale anchored as follows:
  • 1 = Strongly Disagree
  • 2 = Disagree
  • 3 = Slightly Disagree
  • 4 = Slightly Agree
  • 5 = Agree
  • 6 = Strongly Agree
• Scoring and Transformation Protocol:
  • Step 1 (Reverse Coding): Before computing summary scores, the four negatively keyed items (Items 2, 3, 6, and 7) must be reverse-scored so that higher numerical values consistently denote higher perceived competence. The formula is: $$\text{Recoded Score} = 7 – \text{Raw Response}$$ (i.e., a raw score of 1 becomes 6; 2 becomes 5; 3 becomes 4; 4 becomes 3; 5 becomes 2; 6 becomes 1).
  • Step 2 (Item Summation): Sum the four recoded negative items and the four original positive items: $$\text{Total Sum Score} = \text{Item 1} + (7 – \text{Item 2}) + (7 – \text{Item 3}) + \text{Item 4} + \text{Item 5} + (7 – \text{Item 6}) + (7 – \text{Item 7}) + \text{Item 8}$$
    Total PHCS sum scores range from a minimum of 8 to a maximum of 48.
  • Alternative Scoring (Mean Metric): Alternatively, researchers may calculate the arithmetic mean across all 8 recoded items, yielding a mean competence score ranging from 1.0 to 6.0, which facilitates intuitive comparison against the original Likert options.
  • Missing Data Handling: If a respondent completes at least 6 of the 8 items ($ge 75%$ completion), missing values may be imputed using individual mean replacement across the remaining completed items before summing. If more than 2 items are omitted, the protocol is traditionally classified as invalid.
• Score Interpretation:
  • Low Perceived Health Competence (Sum Score 8–24 / Mean 1.00–3.00): Indicates profound feelings of inefficacy, fatalism, and perceived inability to resolve personal health issues. Patients in this range are at elevated risk for non-adherence, depressive demoralization, and poor engagement with self-management plans.
  • Moderate Perceived Health Competence (Sum Score 25–36 / Mean 3.12–4.50): Reflects an intermediate sense of competence; the individual feels capable of handling routine health needs but may experience diminished confidence or frustration in the face of complex or unexpected health setbacks.
  • High Perceived Health Competence (Sum Score 37–48 / Mean 4.62–6.00): Denotes high confidence in managing health problems, achieving self-directed physical goals, and executing medical recommendations. Correlates positively with preventive health activities, active coping, and resilience under chronic illness.

Permissions & Fee and Test Year

The Perceived Health Competence Scale was originally developed and published in 1995 by M. Susan Smith, Kenneth A. Wallston, and Craig A. Smith in the academic journal Health Education Research: Theory & Practice. Under standard psychometric conventions and the professional estate of Dr. Kenneth A. Wallston, the PHCS is placed in the public domain for non-commercial educational, clinical, and academic research purposes. No financial fees, royalties, or formal administrative licensing agreements are required for non-commercial investigators to reproduce or administer the 8 items.

Researchers and clinicians utilizing the PHCS must provide full formal academic citation to the foundational 1995 validation publication (Smith, Wallston, & Smith, 1995). Commercial organizations, proprietary digital health platforms, for-profit mobile applications, or corporate pharmaceutical trial entities wishing to incorporate the instrument into proprietary commercial software suites should consult the relevant academic rights holders or Vanderbilt University’s technology transfer office for commercial licensing terms.

References

• Bandura, A. (1977). Self-efficacy: Toward a unifying theory of behavioral change. Psychological Review, 84(2), 191–215. https://doi.org/10.1037/0033-295X.84.2.191
• Bandura, A. (1986). Social Foundations of Thought and Action: A Social Cognitive Theory. Prentice-Hall.
• Bandura, A. (1997). Self-Efficacy: The Exercise of Control. W. H. Freeman and Company.
• Dempster, M., & Donnelly, M. (2008). Validity of the Perceived Health Competence Scale in a UK primary care setting. Psychology, Health & Medicine, 13(1), 123–127. https://doi.org/10.1080/13548500701328458
• Lazarus, R. S., & Folkman, S. (1984). Stress, Appraisal, and Coping. Springer Publishing Company.
• Marks, G. R., & Lutgendorf, S. K. (1999). Perceived health competence and personality factors differentially predict health behaviors in older adults. Journal of Aging and Health, 11(2), 221–239. https://doi.org/10.1177/089826439901100205
• Rotter, J. B. (1954). Social Learning and Clinical Psychology. Prentice-Hall. https://doi.org/10.1037/10788-000
• Rotter, J. B. (1966). Generalized expectancies for internal versus external control of reinforcement. Psychological Monographs: General and Applied, 80(1), 1–28. https://doi.org/10.1037/h0092976
• Smith, M. S., Wallston, K. A., & Smith, C. A. (1995). The development and validation of the Perceived Health Competence Scale. Health Education Research: Theory & Practice, 10(1), 51–64. https://doi.org/10.1093/her/10.1.51
• Wallston, K. A. (1992). Hocus-pocus, the focus isn’t strictly on locus: Rotter’s social learning theory modified for health. Cognitive Therapy and Research, 16(2), 183–199. https://doi.org/10.1007/BF01173488
• Wallston, K. A., Wallston, B. S., & DeVellis, R. (1978). Development of the Multidimensional Health Locus of Control (MHLC) Scales. Health Education Monographs, 6(2), 160–170. https://doi.org/10.1177/109019817800600107

Items of the Scale