The Experts below are selected from a list of 7506 Experts worldwide ranked by ideXlab platform
Barbara C Tilley - One of the best experts on this subject based on the ideXlab platform.
-
continuous time markov chain approaches for analyzing Transtheoretical Models of health behavioral change a case study and comparison of Model estimations
Statistical Methods in Medical Research, 2018Co-Authors: Wenyaw Chan, Barbara C TilleyAbstract:Continuous time Markov chain Models are frequently employed in medical research to study the disease progression but are rarely applied to the Transtheoretical Model, a psychosocial Model widely used in the studies of health-related outcomes. The Transtheoretical Model often includes more than three states and conceptually allows for all possible instantaneous transitions (referred to as general continuous time Markov chain). This complicates the likelihood function because it involves calculating a matrix exponential that may not be simplified for general continuous time Markov chain Models. We undertook a Bayesian approach wherein we numerically evaluated the likelihood using ordinary differential equation solvers available from the gnu scientific library. We compared our Bayesian approach with the maximum likelihood method implemented with the R package MSM. Our simulation study showed that the Bayesian approach provided more accurate point and interval estimates than the maximum likelihood method, especially in complex continuous time Markov chain Models with five states. When applied to data from a four-state Transtheoretical Model collected from a nutrition intervention study in the next step trial, we observed results consistent with the results of the simulation study. Specifically, the two approaches provided comparable point estimates and standard errors for most parameters, but the maximum likelihood offered substantially smaller standard errors for some parameters. Comparable estimates of the standard errors are obtainable from package MSM, which works only when the Model estimation algorithm converges.
-
continuous time markov chain approaches for analyzing Transtheoretical Models of health behavioral change a case study and comparison of Model estimations
Statistical Methods in Medical Research, 2018Co-Authors: Wenyaw Chan, Barbara C TilleyAbstract:Continuous time Markov chain Models are frequently employed in medical research to study the disease progression but are rarely applied to the Transtheoretical Model, a psychosocial Model widely us...
-
analysis of Transtheoretical Model of health behavioral changes in a nutrition intervention study a continuous time markov chain Model with bayesian approach
Statistics in Medicine, 2015Co-Authors: Wenyaw Chan, Chulin Tsai, Momiao Xiong, Barbara C TilleyAbstract:Continuous time Markov chain (CTMC) Models are often used to study the progression of chronic diseases in medical research but rarely applied to studies of the process of behavioral change. In studies of interventions to modify behaviors, a widely used psychosocial Model is based on the Transtheoretical Model that often has more than three states (representing stages of change) and conceptually permits all possible instantaneous transitions. Very little attention is given to the study of the relationships between a CTMC Model and associated covariates under the framework of Transtheoretical Model. We developed a Bayesian approach to evaluate the covariate effects on a CTMC Model through a log-linear regression link. A simulation study of this approach showed that Model parameters were accurately and precisely estimated. We analyzed an existing data set on stages of change in dietary intake from the Next Step Trial using the proposed method and the generalized multinomial logit Model. We found that the generalized multinomial logit Model was not suitable for these data because it ignores the unbalanced data structure and temporal correlation between successive measurements. Our analysis not only confirms that the nutrition intervention was effective but also provides information on how the intervention affected the transitions among the stages of change. We found that, compared with the control group, subjects in the intervention group, on average, spent substantively less time in the precontemplation stage and were more/less likely to move from an unhealthy/healthy state to a healthy/unhealthy state.
-
analysis of Transtheoretical Model of health behavioral changes in a nutrition intervention study a continuous time markov chain Model with bayesian approach
Statistics in Medicine, 2015Co-Authors: Wenyaw Chan, Chulin Tsai, Momiao Xiong, Barbara C TilleyAbstract:Continuous time Markov chain (CTMC) Models are often used to study the progression of chronic diseases in medical research but rarely applied to studies of the process of behavioral change. In studies of interventions to modify behaviors, a widely used psychosocial Model is based on the Transtheoretical Model that often has more than three states (representing stages of change) and conceptually permits all possible instantaneous transitions. Very little attention is given to the study of the relationships between a CTMC Model and associated covariates under the framework of Transtheoretical Model. We developed a Bayesian approach to evaluate the covariate effects on a CTMC Model through a log-linear regression link. A simulation study of this approach showed that Model parameters were accurately and precisely estimated. We analyzed an existing data set on stages of change in dietary intake from the Next Step Trial using the proposed method and the generalized multinomial logit Model. We found that the generalized multinomial logit Model was not suitable for these data because it ignores the unbalanced data structure and temporal correlation between successive measurements. Our analysis not only confirms that the nutrition intervention was effective but also provides information on how the intervention affected the transitions among the stages of change. We found that, compared with the control group, subjects in the intervention group, on average, spent substantively less time in the precontemplation stage and were more/less likely to move from an unhealthy/healthy state to a healthy/unhealthy state. Copyright © 2015 John Wiley & Sons, Ltd.
Wenyaw Chan - One of the best experts on this subject based on the ideXlab platform.
-
continuous time markov chain approaches for analyzing Transtheoretical Models of health behavioral change a case study and comparison of Model estimations
Statistical Methods in Medical Research, 2018Co-Authors: Wenyaw Chan, Barbara C TilleyAbstract:Continuous time Markov chain Models are frequently employed in medical research to study the disease progression but are rarely applied to the Transtheoretical Model, a psychosocial Model widely used in the studies of health-related outcomes. The Transtheoretical Model often includes more than three states and conceptually allows for all possible instantaneous transitions (referred to as general continuous time Markov chain). This complicates the likelihood function because it involves calculating a matrix exponential that may not be simplified for general continuous time Markov chain Models. We undertook a Bayesian approach wherein we numerically evaluated the likelihood using ordinary differential equation solvers available from the gnu scientific library. We compared our Bayesian approach with the maximum likelihood method implemented with the R package MSM. Our simulation study showed that the Bayesian approach provided more accurate point and interval estimates than the maximum likelihood method, especially in complex continuous time Markov chain Models with five states. When applied to data from a four-state Transtheoretical Model collected from a nutrition intervention study in the next step trial, we observed results consistent with the results of the simulation study. Specifically, the two approaches provided comparable point estimates and standard errors for most parameters, but the maximum likelihood offered substantially smaller standard errors for some parameters. Comparable estimates of the standard errors are obtainable from package MSM, which works only when the Model estimation algorithm converges.
-
continuous time markov chain approaches for analyzing Transtheoretical Models of health behavioral change a case study and comparison of Model estimations
Statistical Methods in Medical Research, 2018Co-Authors: Wenyaw Chan, Barbara C TilleyAbstract:Continuous time Markov chain Models are frequently employed in medical research to study the disease progression but are rarely applied to the Transtheoretical Model, a psychosocial Model widely us...
-
analysis of Transtheoretical Model of health behavioral changes in a nutrition intervention study a continuous time markov chain Model with bayesian approach
Statistics in Medicine, 2015Co-Authors: Wenyaw Chan, Chulin Tsai, Momiao Xiong, Barbara C TilleyAbstract:Continuous time Markov chain (CTMC) Models are often used to study the progression of chronic diseases in medical research but rarely applied to studies of the process of behavioral change. In studies of interventions to modify behaviors, a widely used psychosocial Model is based on the Transtheoretical Model that often has more than three states (representing stages of change) and conceptually permits all possible instantaneous transitions. Very little attention is given to the study of the relationships between a CTMC Model and associated covariates under the framework of Transtheoretical Model. We developed a Bayesian approach to evaluate the covariate effects on a CTMC Model through a log-linear regression link. A simulation study of this approach showed that Model parameters were accurately and precisely estimated. We analyzed an existing data set on stages of change in dietary intake from the Next Step Trial using the proposed method and the generalized multinomial logit Model. We found that the generalized multinomial logit Model was not suitable for these data because it ignores the unbalanced data structure and temporal correlation between successive measurements. Our analysis not only confirms that the nutrition intervention was effective but also provides information on how the intervention affected the transitions among the stages of change. We found that, compared with the control group, subjects in the intervention group, on average, spent substantively less time in the precontemplation stage and were more/less likely to move from an unhealthy/healthy state to a healthy/unhealthy state.
-
analysis of Transtheoretical Model of health behavioral changes in a nutrition intervention study a continuous time markov chain Model with bayesian approach
Statistics in Medicine, 2015Co-Authors: Wenyaw Chan, Chulin Tsai, Momiao Xiong, Barbara C TilleyAbstract:Continuous time Markov chain (CTMC) Models are often used to study the progression of chronic diseases in medical research but rarely applied to studies of the process of behavioral change. In studies of interventions to modify behaviors, a widely used psychosocial Model is based on the Transtheoretical Model that often has more than three states (representing stages of change) and conceptually permits all possible instantaneous transitions. Very little attention is given to the study of the relationships between a CTMC Model and associated covariates under the framework of Transtheoretical Model. We developed a Bayesian approach to evaluate the covariate effects on a CTMC Model through a log-linear regression link. A simulation study of this approach showed that Model parameters were accurately and precisely estimated. We analyzed an existing data set on stages of change in dietary intake from the Next Step Trial using the proposed method and the generalized multinomial logit Model. We found that the generalized multinomial logit Model was not suitable for these data because it ignores the unbalanced data structure and temporal correlation between successive measurements. Our analysis not only confirms that the nutrition intervention was effective but also provides information on how the intervention affected the transitions among the stages of change. We found that, compared with the control group, subjects in the intervention group, on average, spent substantively less time in the precontemplation stage and were more/less likely to move from an unhealthy/healthy state to a healthy/unhealthy state. Copyright © 2015 John Wiley & Sons, Ltd.
James O. Prochaska - One of the best experts on this subject based on the ideXlab platform.
-
decision making in the Transtheoretical Model of behavior change
Medical Decision Making, 2008Co-Authors: James O. ProchaskaAbstract:Decision making is an integral part of the Transtheoretical Model of behavior change. Stage of change represents a temporal dimension for behavior change and has been the key dimension for integrating principles and processes of change from across leading theories of psychotherapy and behavior change. The decision-making variables representing the pros and cons of changing have been found to have systematic relationships across the stages of change for 50 health-related behaviors. Implications of these patterns of relationships are discussed in the context of helping patients make more effective decisions to decrease health risk behaviors and increase health-enhancing behaviors.
-
evaluating theories of health behavior change a hierarchy of criteria applied to the Transtheoretical Model
Applied Psychology, 2008Co-Authors: James O. Prochaska, Julie A Wright, Wayne F VelicerAbstract:The most common criteria recommended by philosophers of science for evaluating theories were organised within a hierarchy ranging from the least to the most risky tests for theories of health behavior change. The hierarchy progressed across: (1) Clarity; (2) Consistency; (3) Parsimony; (4) Testable; (5) Predictive Power; (6) Explanatory Power; (7) Productivity; (8) Generalisable; (9) Integration; (10) Utility; (11) Efficacy; and (12) Impact. The hierarchy was applied to the Transtheoretical Model (TTM) as an example of a health behavior change theory. The application was from the perspective of critics and advocates of TTM. Examples of basic and applied research challenging and supporting TTM across the hierarchy of criteria are presented. The goal is to provide a Model for comparing alternative theories and to evaluate progress across the hierarchy within a particular theory. As theories meet criteria at each step in the hierarchy, the research and applications they generate can have increasing impacts on the science and practice of health behavior change.
-
Transtheoretical Model based multiple behavior intervention for weight management effectiveness on a population basis
Preventive Medicine, 2008Co-Authors: Sara S Johnson, Julie A Wright, James O. Prochaska, Andrea L Paiva, Sharon Dyment, Janice M Prochaska, Janet L Johnson, Carol O Cummins, Karen J ShermanAbstract:Abstract Background. The increasing prevalence of overweight and obesity underscores the need for evidence-based, easily disseminable interventions for weight management that can be delivered on a population basis. The Transtheoretical Model (TTM) offers a promising theoretical framework for multiple behavior weight management interventions. Methods. Overweight or obese adults (BMI 25–39.9; n = 1277) were randomized to no-treatment control or home-based, stage-matched multiple behavior interventions for up to three behaviors related to weight management at 0, 3, 6, and 9 months. All participants were re-assessed at 6, 12, and 24 months. Results. Significant treatment effects were found for healthy eating (47.5% versus 34.3%), exercise (44.90% versus 38.10%), managing emotional distress (49.7% versus 30.30%), and untreated fruit and vegetable intake (48.5% versus 39.0%) progressing to Action/Maintenance at 24 months. The groups differed on weight lost at 24 months. Co-variation of behavior change occurred and was much more pronounced in the treatment group, where individuals progressing to Action/Maintenance for a single behavior were 2.5–5 times more likely to make progress on another behavior. The impact of the multiple behavior intervention was more than three times that of single behavior interventions. Conclusions. This study demonstrates the ability of TTM-based tailored feedback to improve healthy eating, exercise, managing emotional distress, and weight on a population basis. The treatment produced a high level of population impact that future multiple behavior interventions can seek to surpass.
-
a randomized clinical trial of a population and Transtheoretical Model based stress management intervention
Health Psychology, 2006Co-Authors: Kerry E Evers, James O. Prochaska, Leanne M Mauriello, Janet L Johnson, Julie A Padula, Janice M ProchaskaAbstract:Stress has been associated with a variety of chronic and acute conditions and with higher use of health care services. This research reports on 18-month outcomes of a randomized clinical trial of a stress-management program based on the Transtheoretical Model (TTM; J. O. Prochaska & C. C. DiClemente, 1986). A national sample of 1,085 individuals participated (age range = 18-91 years, M = 55.33; 68.9% female, 31.1% male; 84.8% Caucasian; 15.2% non-Caucasian). Both the treatment and control groups received assessments at 0, 6, 12, and 18 months. In addition to the assessments, the treatment group received 3 individualized reports (0, 3, 6 months) and a manual. The 18-month assessment was completed by 778 individuals (72%). A random effects Model indicated that participants completing the study in the treatment group had significantly more individuals reporting effective stress management at follow-up time points than did completers in the control group. Results also indicate that the intervention had significant effects on stress, depression, and specific stress-management behaviors. Results provide evidence for the effectiveness of this TTM population-based stress-management intervention.
-
cluster subtypes within stage of change in a representative sample of smokers
Addictive Behaviors, 2000Co-Authors: Gregory J Norman, Wayne F Velicer, Joseph L Fava, James O. ProchaskaAbstract:In this paper a three-level conceptualization of approaches to matching self-help behavior change strategies to individuals is presented based on the Transtheoretical Model of Change. Two of the Model's intervention approaches, tailoring to Stage-of-Change and creating completely individualized interventions, have already been developed and implemented in previous research. A third intervention approach, in between stage-tailored and individualized, is targeting subtype groups within each Stage of Change. The subtype targeted intervention approach is in the initial development stage of empirically determining and validating the stage subtypes. Three studies are presented which investigate stage subtypes within a representative sample of 4,144 smokers in the Precontemplation, Contemplation, and Preparation Stages of Change. Within each Stage-of-Change study, two cluster analyses were performed using the Pros, Cons, and Situational Temptations from the Transtheoretical Model to establish cluster replicability. Cluster solutions were externally validated using the 10 Processes of Change and 2 smoking behavior variables. Four distinct subtypes were found in Precontemplation and Contemplation, and five subtypes were found in Preparation. These subtypes closely replicate subtypes previously found in a convenience sample of smokers and provide strong evidence for the existence of subtypes within the first three Stages of Change.
Claudio R Nigg - One of the best experts on this subject based on the ideXlab platform.
-
health promoting and health risk behaviors theory driven analyses of multiple health behavior change in three international samples
International Journal of Behavioral Medicine, 2012Co-Authors: Sonia Lippke, Claudio R Nigg, Jason E MaddockAbstract:Background Co-occurrence of different behaviors was investigated using the theoretical underpinnings of the Transtheoretical Model, the Theory of Triadic Influence and the concept of Transfer.
-
a research agenda to examine the efficacy and relevance of the Transtheoretical Model for physical activity behavior
Psychology of Sport and Exercise, 2011Co-Authors: Claudio R Nigg, Robert W Motl, Caroline C Horwath, Karly S Geller, Kristin K Wertin, Rod K DishmanAbstract:Regular physical activity (PA) decreases the risk of several chronic diseases including some cancers, type II diabetes, obesity, and cardiovascular disease; however, the majority of US adults are not meeting the recommended levels to experience these benefits. To address this public health concern, the underlying mechanisms for behavior change need to be understood, translated and disseminated into appropriately tailored interventions. The Transtheoretical Model (TTM) provides a framework for both the conceptualization and measurement of behavior change, as well as facilitating promotion strategies that are individualized and easily adapted. The purpose of this manuscript is to present the constructs of the TTM as they relate to PA behavior change. We begin with a brief synopsis of recent examinations of the TTM constructs and their application. Subsequent to its introduction, we specifically present the TTM within the PA context and discuss its application and usefulness to researchers and practitioners. Criticisms of the TTM are also noted and presented as opportunities for future research to enhance the valid application of the TTM. We offer general study design recommendations to appropriately test the hypothesized relationships within the Model. With further examinations using appropriate study design and statistical analyses, we believe the TTM has the potential to advance the public health impact of future PA promotion interventions.
-
Using Constructs of the Transtheoretical Model to Predict Classes of Change in Regular Physical Activity: A Multi-Ethnic Longitudinal Cohort Study
Annals of Behavioral Medicine, 2010Co-Authors: Rod K Dishman, Robert W Motl, Robert J. Vandenberg, Claudio R NiggAbstract:Explaining variation in meeting recommended levels of physical activity across time is important for the design of effective public health interventions. To Model longitudinal change in constructs of the Transtheoretical Model and test their hypothesized relations with change in meeting the Healthy People 2010 guidelines for regular participation in moderate or vigorous physical activity, a cohort ( N = 497) from a random, multi-ethnic sample of 700 adults living in Hawaii was assessed at 6-month intervals three or more times for 2 years. Latent class growth Modeling was used to classify people according to their initial levels and trajectories of change in the Transtheoretical variables and separately according to whether they met the physical activity guideline each time. Relations of the variables and their change with classes of meeting the guideline were then tested using multinomial logistic regression. Despite declines or no change in mean scores for all Transtheoretical variables except self-efficacy, participants who maintained or attained the physical activity guideline were more likely to retain higher scores across the 2 years of observation. The usefulness of Transtheoretical constructs for predicting maintenance of, or increases in, public health levels of physical activity was generally supported. These longitudinal results support earlier cross-sectional findings which indicate that, contrary to theory, people appear to use both experiential and behavioral processes while they attempt to increase or maintain their physical activity.
-
failure of post action stages of the Transtheoretical Model to predict change in regular physical activity a multiethnic cohort study
Annals of Behavioral Medicine, 2009Co-Authors: Rod K Dishman, Nathaniel J Thom, Cherie Rooks, Robert W Motl, Caroline C Horwath, Claudio R NiggAbstract:Predicting variation in meeting recommended levels of physical activity is important for public health evaluation. The purpose of this study is to determine the predictive value of stages of the Transtheoretical Model (TTM) for classifying people who meet the US Healthy People 2010 guideline for regular physical activity. A cohort (N = 497) from a random, multiethnic sample of 700 adults living in Hawaii was assessed at 6-month intervals three or more times for 2 years. Latent transition analysis was used to classify people according to TTM stages and separately according to whether they met the guideline. The predictive value of pre- vs. post-action stages was then tested. Stages were more likely to falsely classify people as meeting the guideline than to falsely classify them as not meeting it. Probabilities of predicting 6-month transitions were about 50% for the stable class of meeting the guideline each time and just 25% for transitions between meeting and not meeting the guideline. The TTM post-action stages had limited usefulness in this cohort. Further longitudinal study is needed to determine whether TTM stages can accurately classify transitions from physical inactivity to physical activity below recommended levels.
-
the theory of planned behavior within the stages of the Transtheoretical Model latent structural Modeling of stage specific prediction patterns in physical activity
Structural Equation Modeling, 2007Co-Authors: Sonia Lippke, Claudio R Nigg, Jay E MaddockAbstract:This is the first study to test whether the stages of change of the Transtheoretical Model are qualitatively different through exploring discontinuity patterns in theory of planned behavior (TPB) variables using latent multigroup structural equation Modeling (MSEM) with AMOS. Discontinuity patterns in terms of latent means and prediction patterns for the different stage groups were examined. Adults (n = 3,462) were assessed on their physical activity stages of change and TPB variables. The TPB was separately examined within the five stage groups. The TPB measurement Model fit was acceptable. Latent mean analyses with post-hoc contrast and MSEM indicated discontinuity patterns. Results underscore the qualitative differences between the stages that may guide further research and the design of interventions integrating the approaches.
Rod K Dishman - One of the best experts on this subject based on the ideXlab platform.
-
a research agenda to examine the efficacy and relevance of the Transtheoretical Model for physical activity behavior
Psychology of Sport and Exercise, 2011Co-Authors: Claudio R Nigg, Robert W Motl, Caroline C Horwath, Karly S Geller, Kristin K Wertin, Rod K DishmanAbstract:Regular physical activity (PA) decreases the risk of several chronic diseases including some cancers, type II diabetes, obesity, and cardiovascular disease; however, the majority of US adults are not meeting the recommended levels to experience these benefits. To address this public health concern, the underlying mechanisms for behavior change need to be understood, translated and disseminated into appropriately tailored interventions. The Transtheoretical Model (TTM) provides a framework for both the conceptualization and measurement of behavior change, as well as facilitating promotion strategies that are individualized and easily adapted. The purpose of this manuscript is to present the constructs of the TTM as they relate to PA behavior change. We begin with a brief synopsis of recent examinations of the TTM constructs and their application. Subsequent to its introduction, we specifically present the TTM within the PA context and discuss its application and usefulness to researchers and practitioners. Criticisms of the TTM are also noted and presented as opportunities for future research to enhance the valid application of the TTM. We offer general study design recommendations to appropriately test the hypothesized relationships within the Model. With further examinations using appropriate study design and statistical analyses, we believe the TTM has the potential to advance the public health impact of future PA promotion interventions.
-
Using Constructs of the Transtheoretical Model to Predict Classes of Change in Regular Physical Activity: A Multi-Ethnic Longitudinal Cohort Study
Annals of Behavioral Medicine, 2010Co-Authors: Rod K Dishman, Robert W Motl, Robert J. Vandenberg, Claudio R NiggAbstract:Explaining variation in meeting recommended levels of physical activity across time is important for the design of effective public health interventions. To Model longitudinal change in constructs of the Transtheoretical Model and test their hypothesized relations with change in meeting the Healthy People 2010 guidelines for regular participation in moderate or vigorous physical activity, a cohort ( N = 497) from a random, multi-ethnic sample of 700 adults living in Hawaii was assessed at 6-month intervals three or more times for 2 years. Latent class growth Modeling was used to classify people according to their initial levels and trajectories of change in the Transtheoretical variables and separately according to whether they met the physical activity guideline each time. Relations of the variables and their change with classes of meeting the guideline were then tested using multinomial logistic regression. Despite declines or no change in mean scores for all Transtheoretical variables except self-efficacy, participants who maintained or attained the physical activity guideline were more likely to retain higher scores across the 2 years of observation. The usefulness of Transtheoretical constructs for predicting maintenance of, or increases in, public health levels of physical activity was generally supported. These longitudinal results support earlier cross-sectional findings which indicate that, contrary to theory, people appear to use both experiential and behavioral processes while they attempt to increase or maintain their physical activity.
-
failure of post action stages of the Transtheoretical Model to predict change in regular physical activity a multiethnic cohort study
Annals of Behavioral Medicine, 2009Co-Authors: Rod K Dishman, Nathaniel J Thom, Cherie Rooks, Robert W Motl, Caroline C Horwath, Claudio R NiggAbstract:Predicting variation in meeting recommended levels of physical activity is important for public health evaluation. The purpose of this study is to determine the predictive value of stages of the Transtheoretical Model (TTM) for classifying people who meet the US Healthy People 2010 guideline for regular physical activity. A cohort (N = 497) from a random, multiethnic sample of 700 adults living in Hawaii was assessed at 6-month intervals three or more times for 2 years. Latent transition analysis was used to classify people according to TTM stages and separately according to whether they met the guideline. The predictive value of pre- vs. post-action stages was then tested. Stages were more likely to falsely classify people as meeting the guideline than to falsely classify them as not meeting it. Probabilities of predicting 6-month transitions were about 50% for the stable class of meeting the guideline each time and just 25% for transitions between meeting and not meeting the guideline. The TTM post-action stages had limited usefulness in this cohort. Further longitudinal study is needed to determine whether TTM stages can accurately classify transitions from physical inactivity to physical activity below recommended levels.
