PROFESSIONAL PRACTICE
Commitment to Health Theory: A Graphic Model Cynthia W. Kelly, PhD, RN, CNL
Graphic models can improve understanding of theoretical concepts and the relationship between concepts. This article introduces a model of Commitment to Health Theory, which describes the process of behavior change from action to the maintenance stage of change. Commitment to health means that a new or modified health behavior will be used regardless of socioeconomic factors, race, gender, employment category, and age. Findings were based on three cross-sectional survey studies of approximately 1,085 predominantly manufacturing workers sampled from across the United States. Commitment to Health Theory was used to identify those in the action stage of change with mid-level commitment and predict the likelihood of successfully changing health behavior. Monitoring levels of commitment to health can determine appropriate intervention strategies to assist clients who currently exhibit unhealthy diet and exercise behaviors. [Workplace Health Saf 2014;62(2):51-54.]
O
ry, Jordan, and Bazzarre (2002) and Palmeira et al. (2007) identified the Transtheoretical Model of Behavior Change (TTM) as one of the most effective theoretical frameworks for understanding the health behavior change process. The TTM is based on stages of change and assumes that the stages represent a continuum ABOUT THE AUTHOR
Dr. Kelly is Associate Professor, University of Alabama Capstone College of Nursing, Tuscaloosa, Alabama. Submitted: September 12, 2013; Accepted: October 9, 2013; Posted online February 7, 2014 Supported in part by NIOSH Pilot Research Project Training Program Grant #T42/ CCT510420 through the University of Cincinnati Education and Research Center (UC/ERC). The author has no financial or proprietary interest in the materials presented herein. Correspondence: Cynthia W. Kelly, PhD, RN, CNL, The University of Alabama, Capstone College of Nursing, Box 870358, Tuscaloosa, AL 35487. E-mail: [email protected]
ranging from “no intent to change” to the new behavior “integrated into daily life.” Other variables associated with the TTM include intervention strategies or processes of change, self-efficacy or confidence, temptation strength, and decisional balance or the importance of change (Kelly, 2001; Velicer, Prochaska, Fava, Norman, & Redding, 1998). Derived from TTM concepts, Commitment to Health Theory (Kelly, 2001) includes stages of change, decisional balance, and self-efficacy. Previous research (Kelly, 2001) indicated that individuals’ levels of commitment toward a health behavior best predicted the likelihood of health behavior actions. Commitment to Health, defined herein as commitment to perform a behavior (i.e., self-directed goal setting), correlates with an individual’s actual stage of change as described by the TTM and predicts the likeli-
WORKPLACE HEALTH & SAFETY • VOL. 62, NO. 2, 2014
hood of moving to a more active stage of change (Kelly, 2001). COMMITMENT TO HEALTH THEORY Commitment to Health Theory is specific for individuals in the action stage of change, especially those who have started a new behavior but risk relapse (Kelly, 2008). In Commitment to Health Theory, the stageof-change variable is a self-reported categorical measure that assesses behavioral actions within a specified time frame (Kelly, 2005). An individual’s commitment to health, defined as internal resolve to perform a health behavior (Kelly, 2001), can be measured using the Commitment to Health Scale, which classifies clients into three categories: 1. Low level of commitment: individual may or may not consciously intend to perform health behaviors, but is unable to follow through with a behavior change for more than 1 month. Those with a low level of commitment have scores at or below 0 on the Rasch rating scale. 2. Middle level of commitment: individual intends to perform health behaviors, but is either inconsistent in performance or is unable to sustain performance for more than 6 months. These individuals have Rasch scores between 0 and 1. 3. High level of commitment: individual consistently performs a wide range of healthy behaviors for more than 6 months. Rasch
51
PROFESSIONAL PRACTICE
Figure 1. Commitment to Health Theory behavior change model.
scores are 1 or higher (Kelly, 2001, 2005, 2008). The relative simplicity of the Commitment to Health Theory can be better understood with a visual aid that organizes the concepts, identifies concept attributes, and indicates the directional relationship between the concepts (All, Huycke, & Fisher, 2003; Mayer, Steinhoff, Bower, & Mars, 1995; Novak, 2002). The Commitment to Health Model (Kelly, 2008) presents the pre-action, action, and maintenance stages of change for a specific health behavior (Figure 1). Movement occurs between stages of change as commitment to health increases and the behavior is fully integrated into activities of daily living (maintenance stage) or as individuals relapse into former behaviors. Change from the action stage to the maintenance stage is hypothesized to take approximately 6 months, depending on the behavior (Figure 1). The Commitment to Health Model identified three categories of change stages: the pre-action stage (includes precontemplation, contemplation, and preparation), the action stage, and the maintenance stage. Arrows indicate a linear relationship of stage movement as progress
52
and relapse (Velicer et al., 1998). No time element exists for the pre-action stage of change. The action stage of change is hypothesized to be at least 6 months for most behaviors, but may last 2 years for smoking cessation (Velicer et al., 1998) before reaching the maintenance stage. The Commitment to Health Scale, based on scores and selfreported stages of change, can indicate an individual’s level of commitment to health. A low level of commitment indicates that those in the action stage are most at risk for relapse to pre-action stages. Those with high-level commitment scores are most likely moving to the maintenance stage of change. Those with middle-level commitment scores range between pre-action and maintenance. Health care providers can use the stage of change categories and commitment scores to individualize treatment using strategies tailored to the processes of change and motivational therapeutic communication techniques. METHODS Three studies were completed between 1998 and 2001. The total population for the three studies included 2,923 potential participants,
with a final sample of 1,085 representing 37% of the study population (Kelly, 2001, 2008). The first study included 623 participants, the second 2,000 participants, and the third 300 participants (Kelly, 2001, 2008). The majority of the study population were manufacturing employees and office staff from plants in Georgia, Pennsylvania, Ohio, Missouri, and California. Participation was voluntary and approved by the institutional review board of a major research university. Participant response was evidence of informed consent, participation was confidential, responses were collected anonymously, and data were presented as summary information. Of the participants, 59% (n = 643) were male and 41% were (n = 442) female. The average age was 40 years ± 10 years (range: 18 to 65 years). For known race, 65% (603 of 927) were white, 25% (230 of 927) were African American, and 10% (93 of 927) were Latino/Hispanic, Asian, or unknown race. Eighty-one percent (749 of 927) were hourly workers (predominantly manufacturing workers) and 19% (182 of 927) were exempt employees. Cross-sectional and survey methods were used to conduct the research. A survey of health behaviors and demographic information was
Copyright © American Association of Occupational Health Nurses, Inc.
PROFESSIONAL PRACTICE
collected in addition to the Commitment to Health Scale items (Kelly, 2001, 2005). A survey was mailed to all employees of the study sites; responses were mailed to the study assistant in unmarked prestamped envelopes. Workers could return a separate postcard requesting a heart-shaped stress ball. No connection was made between the survey and the postcard, and the names of those who received the stress ball were not recorded. The demographic and scale data were analyzed using Pearson’s product moment and Spearman’s rank order correlations depending on the type of data, rank order or continuous. Concept validity was assessed using factor analysis. Internal consistency reliability was assessed using Cronbach’s alpha. Rasch rating scale method was also used to develop the Commitment to Health Scale and identify the range of commitment level categories. Details of the Rasch analysis can be found in previous publications (Kelly, 2001, 2005, 2008). RESULTS The results of this research study indicated a new concept not previously identified (Kelly, 2001, 2008). In all three studies, the commitment to health behavior items demonstrated concept validity (Kelly, 2001). The final study tested the predictability of the commitment to health concept, using the Rasch rating scale method. The Rasch method was used to determine whether a model of predicted item structures would be supported when compared to actual participant responses. In other words, the theoretical ordering of items was substantiated by the observed pattern of reported item ordering. Standardized scale scores were then used to determine whether the scale scores predicted self-reported health behaviors (Kelly, 2001) using stepwise polytomous logistic regression analysis. Commitment to health scores predicted reported behaviors for single target health behaviors, except for smoking behaviors. Table 1 presents the results of Wald chi-square analysis (Kelly, 2008).
Table 1
Wald Chi-square Analysis Results Behavior
df
R2
p
Healthy exercise (n = 63)
1
12.97
.0003
Healthy diet (n = 91)
1
12.03
.0005
Former smoking (n = 22)
1
2.92
.087
Never smoked (n = 96)
1
11.77
.0006
Further descriptive analysis plotted participant scores with Commitment to Health item weights. It was hypothesized that a linear relationship would exist between participant scores and low- to high-level commitment items. The hypothesized relationship was supported. Those participants with high-level commitment were found to have scores in the +1 and above range, those with low-level commitment in the -1 or lower range, and those with mediumlevel commitment between -1 and +1 (Kelly, 2001, 2008). Based on these findings, Commitment to Health Theory is predictive for those currently in the action stage of health behavior change. Limitations to adopting this theory are based on the methodological constraints and the exploratory nature of the research studies. Additional research is needed to determine whether the Commitment to Health concept can predict behavior change over time and in critical populations. DISCUSSION Empirical findings from this and more recent research (Shin, Hur, Pender, Jang, & Kim, 2004; Shin, Yun, Jang, & Lim, 2006), along with use of a visual aid (graphic model), assist clinicians to understand the main concepts and the potential of theoretical applications (All et al., 2003; Mayer et al., 1995; Novak, 2002). The model can be used as a stage-based guide to direct clinicians using health promotion interventions—especially for clients assuming new behaviors in the action stage of change and with middle-level scores in Commitment to Health. Clinicians must work more closely
WORKPLACE HEALTH & SAFETY • VOL. 62, NO. 2, 2014
with middle-category clients to support commitment and avoid relapse into past unhealthy behaviors. This model also appeals to nurses as a teaching and clinical aid. Nurses with limited resources will benefit by characterizing individual clients’ potential for change and identifying appropriate interventions. By tracking changes in clients’ levels of commitment to health, nurses can better measure their effectiveness in assisting individuals in the process of changing unhealthy behaviors to new lifelong healthy behaviors. Having a model to better visualize the theory, concepts, and relationships should make Commitment to Health Theory more accessible to students learning to critique middle-range theories. Increasing the number of those clinicians and researchers exposed to the theory will generate scholarly critiques, theory testing, and refinement of the theory, which in turn will inform healthpromotion policies by adding to the scientific knowledge about health behavior change. REFERENCES
All, A. C., Huycke, L. I., & Fisher, M. J. (2003). Instructional tools for nursing education: Concept maps. Nursing Education Perspectives, 24, 311-317. Kelly, C. W. (2001). Measuring health behavior change (Unpublished doctoral dissertation). University of Cincinnati, Cincinnati, OH. Kelly, C. W. (2005). Commitment to health scale. Journal of Nursing Measurement, 13, 219-299. Kelly, C. W. (2008). Commitment to health theory. Research and Theory for Nursing Practice, 22, 148-160. doi: 10.1891/08897182.22.2.148. Mayer, R. E., Steinhoff, K., Bower, G., & Mars, R. (1995). A generative theory of textbook design: Using annotated illustra-
53
PROFESSIONAL PRACTICE
tions to foster meaningful learning of science text. Education Technology Research and Development, 43, 31-43. Novak, J. D. (2002). Meaningful learning: The essential factor for conceptual change in limited or inappropriate propositional hierarchies leading to empowerment of learners. Science Education, 86, 548-571. doi: 10.1002/sce 10032.10032 Ory, M. G., Jordan, P. J., & Bazzarre, T. (2002). The behavior change consortium: Setting the stage for a new century of health behavior-change research. Health Education, 17, 500-511.
54
Palmeira, A. L., Teixeira, P. J., Branco, T. L., Martins, S. S., Minderico, C. S., Barata, J. T., . . . Sardinha, L. B. (2007). Predicting short-term weight loss using four leading health behavior change theories. International Journal of Behavioral Nutrition and Physical Activity, 4, 14. doi: 101186/14795868-4-14. Shin, Y. H., Hur, H. K., Pender, N. J., Jang, H. J., & Kim, M. S. (2004). Exercise selfefficacy, exercise benefits and barriers, and commitment to a plan for exercise among Korean women with osteoporosis and osteoarthritis. International Journal
of Nursing Studies, 43, 3-10. doi: 10.1016/ jijnurstu.2004.10.008 Shin, Y. H., Yun, S. K., Jang, H. J., & Lim, J. H. (2006). A tailored program for the promotion of physical exercise among Korean adults with chronic diseases. Applied Nursing Research, 19, 88-94. doi: 10.1016/j.apnr.2005.01.004 Velicer, W. F., Prochaska, J. O., Fava, J. L., Norman, G. J., & Redding, C. A. (1998). Detailed overview of the Transtheoretical Model. Retrieved from: http://www.uri.edu/ research/cprc/TTM/detailedoverview.htm
Copyright © American Association of Occupational Health Nurses, Inc.
Commitment to Health Theory: A Graphic Model Cynthia W. Kelly, PhD, RN, CNL
Graphic models can improve understanding of theoretical concepts and the relationship between concepts. This article introduces a model of Commitment to Health Theory, which describes the process of behavior change from action to the maintenance stage of change. Commitment to health means that a new or modified health behavior will be used regardless of socioeconomic factors, race, gender, employment category, and age. Findings were based on three cross-sectional survey studies of approximately 1,085 predominantly manufacturing workers sampled from across the United States. Commitment to Health Theory was used to identify those in the action stage of change with mid-level commitment and predict the likelihood of successfully changing health behavior. Monitoring levels of commitment to health can determine appropriate intervention strategies to assist clients who currently exhibit unhealthy diet and exercise behaviors. [Workplace Health Saf 2014;62(2):51-54.]
O
ry, Jordan, and Bazzarre (2002) and Palmeira et al. (2007) identified the Transtheoretical Model of Behavior Change (TTM) as one of the most effective theoretical frameworks for understanding the health behavior change process. The TTM is based on stages of change and assumes that the stages represent a continuum ABOUT THE AUTHOR
Dr. Kelly is Associate Professor, University of Alabama Capstone College of Nursing, Tuscaloosa, Alabama. Submitted: September 12, 2013; Accepted: October 9, 2013; Posted online February 7, 2014 Supported in part by NIOSH Pilot Research Project Training Program Grant #T42/ CCT510420 through the University of Cincinnati Education and Research Center (UC/ERC). The author has no financial or proprietary interest in the materials presented herein. Correspondence: Cynthia W. Kelly, PhD, RN, CNL, The University of Alabama, Capstone College of Nursing, Box 870358, Tuscaloosa, AL 35487. E-mail: [email protected]
ranging from “no intent to change” to the new behavior “integrated into daily life.” Other variables associated with the TTM include intervention strategies or processes of change, self-efficacy or confidence, temptation strength, and decisional balance or the importance of change (Kelly, 2001; Velicer, Prochaska, Fava, Norman, & Redding, 1998). Derived from TTM concepts, Commitment to Health Theory (Kelly, 2001) includes stages of change, decisional balance, and self-efficacy. Previous research (Kelly, 2001) indicated that individuals’ levels of commitment toward a health behavior best predicted the likelihood of health behavior actions. Commitment to Health, defined herein as commitment to perform a behavior (i.e., self-directed goal setting), correlates with an individual’s actual stage of change as described by the TTM and predicts the likeli-
WORKPLACE HEALTH & SAFETY • VOL. 62, NO. 2, 2014
hood of moving to a more active stage of change (Kelly, 2001). COMMITMENT TO HEALTH THEORY Commitment to Health Theory is specific for individuals in the action stage of change, especially those who have started a new behavior but risk relapse (Kelly, 2008). In Commitment to Health Theory, the stageof-change variable is a self-reported categorical measure that assesses behavioral actions within a specified time frame (Kelly, 2005). An individual’s commitment to health, defined as internal resolve to perform a health behavior (Kelly, 2001), can be measured using the Commitment to Health Scale, which classifies clients into three categories: 1. Low level of commitment: individual may or may not consciously intend to perform health behaviors, but is unable to follow through with a behavior change for more than 1 month. Those with a low level of commitment have scores at or below 0 on the Rasch rating scale. 2. Middle level of commitment: individual intends to perform health behaviors, but is either inconsistent in performance or is unable to sustain performance for more than 6 months. These individuals have Rasch scores between 0 and 1. 3. High level of commitment: individual consistently performs a wide range of healthy behaviors for more than 6 months. Rasch
51
PROFESSIONAL PRACTICE
Figure 1. Commitment to Health Theory behavior change model.
scores are 1 or higher (Kelly, 2001, 2005, 2008). The relative simplicity of the Commitment to Health Theory can be better understood with a visual aid that organizes the concepts, identifies concept attributes, and indicates the directional relationship between the concepts (All, Huycke, & Fisher, 2003; Mayer, Steinhoff, Bower, & Mars, 1995; Novak, 2002). The Commitment to Health Model (Kelly, 2008) presents the pre-action, action, and maintenance stages of change for a specific health behavior (Figure 1). Movement occurs between stages of change as commitment to health increases and the behavior is fully integrated into activities of daily living (maintenance stage) or as individuals relapse into former behaviors. Change from the action stage to the maintenance stage is hypothesized to take approximately 6 months, depending on the behavior (Figure 1). The Commitment to Health Model identified three categories of change stages: the pre-action stage (includes precontemplation, contemplation, and preparation), the action stage, and the maintenance stage. Arrows indicate a linear relationship of stage movement as progress
52
and relapse (Velicer et al., 1998). No time element exists for the pre-action stage of change. The action stage of change is hypothesized to be at least 6 months for most behaviors, but may last 2 years for smoking cessation (Velicer et al., 1998) before reaching the maintenance stage. The Commitment to Health Scale, based on scores and selfreported stages of change, can indicate an individual’s level of commitment to health. A low level of commitment indicates that those in the action stage are most at risk for relapse to pre-action stages. Those with high-level commitment scores are most likely moving to the maintenance stage of change. Those with middle-level commitment scores range between pre-action and maintenance. Health care providers can use the stage of change categories and commitment scores to individualize treatment using strategies tailored to the processes of change and motivational therapeutic communication techniques. METHODS Three studies were completed between 1998 and 2001. The total population for the three studies included 2,923 potential participants,
with a final sample of 1,085 representing 37% of the study population (Kelly, 2001, 2008). The first study included 623 participants, the second 2,000 participants, and the third 300 participants (Kelly, 2001, 2008). The majority of the study population were manufacturing employees and office staff from plants in Georgia, Pennsylvania, Ohio, Missouri, and California. Participation was voluntary and approved by the institutional review board of a major research university. Participant response was evidence of informed consent, participation was confidential, responses were collected anonymously, and data were presented as summary information. Of the participants, 59% (n = 643) were male and 41% were (n = 442) female. The average age was 40 years ± 10 years (range: 18 to 65 years). For known race, 65% (603 of 927) were white, 25% (230 of 927) were African American, and 10% (93 of 927) were Latino/Hispanic, Asian, or unknown race. Eighty-one percent (749 of 927) were hourly workers (predominantly manufacturing workers) and 19% (182 of 927) were exempt employees. Cross-sectional and survey methods were used to conduct the research. A survey of health behaviors and demographic information was
Copyright © American Association of Occupational Health Nurses, Inc.
PROFESSIONAL PRACTICE
collected in addition to the Commitment to Health Scale items (Kelly, 2001, 2005). A survey was mailed to all employees of the study sites; responses were mailed to the study assistant in unmarked prestamped envelopes. Workers could return a separate postcard requesting a heart-shaped stress ball. No connection was made between the survey and the postcard, and the names of those who received the stress ball were not recorded. The demographic and scale data were analyzed using Pearson’s product moment and Spearman’s rank order correlations depending on the type of data, rank order or continuous. Concept validity was assessed using factor analysis. Internal consistency reliability was assessed using Cronbach’s alpha. Rasch rating scale method was also used to develop the Commitment to Health Scale and identify the range of commitment level categories. Details of the Rasch analysis can be found in previous publications (Kelly, 2001, 2005, 2008). RESULTS The results of this research study indicated a new concept not previously identified (Kelly, 2001, 2008). In all three studies, the commitment to health behavior items demonstrated concept validity (Kelly, 2001). The final study tested the predictability of the commitment to health concept, using the Rasch rating scale method. The Rasch method was used to determine whether a model of predicted item structures would be supported when compared to actual participant responses. In other words, the theoretical ordering of items was substantiated by the observed pattern of reported item ordering. Standardized scale scores were then used to determine whether the scale scores predicted self-reported health behaviors (Kelly, 2001) using stepwise polytomous logistic regression analysis. Commitment to health scores predicted reported behaviors for single target health behaviors, except for smoking behaviors. Table 1 presents the results of Wald chi-square analysis (Kelly, 2008).
Table 1
Wald Chi-square Analysis Results Behavior
df
R2
p
Healthy exercise (n = 63)
1
12.97
.0003
Healthy diet (n = 91)
1
12.03
.0005
Former smoking (n = 22)
1
2.92
.087
Never smoked (n = 96)
1
11.77
.0006
Further descriptive analysis plotted participant scores with Commitment to Health item weights. It was hypothesized that a linear relationship would exist between participant scores and low- to high-level commitment items. The hypothesized relationship was supported. Those participants with high-level commitment were found to have scores in the +1 and above range, those with low-level commitment in the -1 or lower range, and those with mediumlevel commitment between -1 and +1 (Kelly, 2001, 2008). Based on these findings, Commitment to Health Theory is predictive for those currently in the action stage of health behavior change. Limitations to adopting this theory are based on the methodological constraints and the exploratory nature of the research studies. Additional research is needed to determine whether the Commitment to Health concept can predict behavior change over time and in critical populations. DISCUSSION Empirical findings from this and more recent research (Shin, Hur, Pender, Jang, & Kim, 2004; Shin, Yun, Jang, & Lim, 2006), along with use of a visual aid (graphic model), assist clinicians to understand the main concepts and the potential of theoretical applications (All et al., 2003; Mayer et al., 1995; Novak, 2002). The model can be used as a stage-based guide to direct clinicians using health promotion interventions—especially for clients assuming new behaviors in the action stage of change and with middle-level scores in Commitment to Health. Clinicians must work more closely
WORKPLACE HEALTH & SAFETY • VOL. 62, NO. 2, 2014
with middle-category clients to support commitment and avoid relapse into past unhealthy behaviors. This model also appeals to nurses as a teaching and clinical aid. Nurses with limited resources will benefit by characterizing individual clients’ potential for change and identifying appropriate interventions. By tracking changes in clients’ levels of commitment to health, nurses can better measure their effectiveness in assisting individuals in the process of changing unhealthy behaviors to new lifelong healthy behaviors. Having a model to better visualize the theory, concepts, and relationships should make Commitment to Health Theory more accessible to students learning to critique middle-range theories. Increasing the number of those clinicians and researchers exposed to the theory will generate scholarly critiques, theory testing, and refinement of the theory, which in turn will inform healthpromotion policies by adding to the scientific knowledge about health behavior change. REFERENCES
All, A. C., Huycke, L. I., & Fisher, M. J. (2003). Instructional tools for nursing education: Concept maps. Nursing Education Perspectives, 24, 311-317. Kelly, C. W. (2001). Measuring health behavior change (Unpublished doctoral dissertation). University of Cincinnati, Cincinnati, OH. Kelly, C. W. (2005). Commitment to health scale. Journal of Nursing Measurement, 13, 219-299. Kelly, C. W. (2008). Commitment to health theory. Research and Theory for Nursing Practice, 22, 148-160. doi: 10.1891/08897182.22.2.148. Mayer, R. E., Steinhoff, K., Bower, G., & Mars, R. (1995). A generative theory of textbook design: Using annotated illustra-
53
PROFESSIONAL PRACTICE
tions to foster meaningful learning of science text. Education Technology Research and Development, 43, 31-43. Novak, J. D. (2002). Meaningful learning: The essential factor for conceptual change in limited or inappropriate propositional hierarchies leading to empowerment of learners. Science Education, 86, 548-571. doi: 10.1002/sce 10032.10032 Ory, M. G., Jordan, P. J., & Bazzarre, T. (2002). The behavior change consortium: Setting the stage for a new century of health behavior-change research. Health Education, 17, 500-511.
54
Palmeira, A. L., Teixeira, P. J., Branco, T. L., Martins, S. S., Minderico, C. S., Barata, J. T., . . . Sardinha, L. B. (2007). Predicting short-term weight loss using four leading health behavior change theories. International Journal of Behavioral Nutrition and Physical Activity, 4, 14. doi: 101186/14795868-4-14. Shin, Y. H., Hur, H. K., Pender, N. J., Jang, H. J., & Kim, M. S. (2004). Exercise selfefficacy, exercise benefits and barriers, and commitment to a plan for exercise among Korean women with osteoporosis and osteoarthritis. International Journal
of Nursing Studies, 43, 3-10. doi: 10.1016/ jijnurstu.2004.10.008 Shin, Y. H., Yun, S. K., Jang, H. J., & Lim, J. H. (2006). A tailored program for the promotion of physical exercise among Korean adults with chronic diseases. Applied Nursing Research, 19, 88-94. doi: 10.1016/j.apnr.2005.01.004 Velicer, W. F., Prochaska, J. O., Fava, J. L., Norman, G. J., & Redding, C. A. (1998). Detailed overview of the Transtheoretical Model. Retrieved from: http://www.uri.edu/ research/cprc/TTM/detailedoverview.htm
Copyright © American Association of Occupational Health Nurses, Inc.
