To prospectively determine clinical and biochemical characteristics associated with the developme... more To prospectively determine clinical and biochemical characteristics associated with the development of peripheral neuropathy, loss of protective sensation, and foot ulceration in persons with type 2 diabetes mellitus (DM) over 7 years. Graded monofilament (MF) testing, vibration perception threshold, and neuropathy symptom questionnaires were undertaken in 206 participants with type 2 DM without peripheral vascular disease or history of foot ulceration and 71 healthy participants without DM at baseline and after 7 years. 6 monthly glycosylated hemoglobin (HbA1c) levels and annual serum lipid profiles were measured during follow-up of those with DM. Incident foot ulceration was recorded at follow-up. Taller stature and higher quartiles of serum triglyceride and HbA1c levels were associated with neuropathy at follow-up (p=0.008). Remission of baseline neuropathy was observed in 7 participants at follow-up. 9 participants with type 2 DM developed foot ulcers by the end of the study, on...
This webfile is designed as a revision aid to some introductory ideas on interval estimation. It ... more This webfile is designed as a revision aid to some introductory ideas on interval estimation. It is intended to supplement a formal encouter with a text book or a set of lectures. These notes are meant to be slightly interactive, mysterious green dots, squares and boxes appear which you can click on to answer questions and check solutions.
Promoting Understanding of Statistics about Society IASE Roundtable Conference
Many interesting social phenomena are innately multidimensional and require suitable data modelli... more Many interesting social phenomena are innately multidimensional and require suitable data modelling tools. Regression modelling (which includes log linear modelling for contingency tables as a special case) is often the „go-to'“ tool. However, much of the math theory was developed for designed experiments (where explanatory variables X are orthogonal and fixed). Conversely, societal data is often observational with random non-orthogonal X. The pedagogic route to data modelling usually starts with linear models before the introduction of the generalised linear models that can address contingency tables. Whilst good textbooks do feature caveats, the search for a parsimonious model is often carried out in a manner that may promote unsafe interpretation of observational data. This poster tries to present a case for a reform in the teaching of regression for observational data.
postgraduate and undergraduate teacher training courses in mathematics and other relevant subject... more postgraduate and undergraduate teacher training courses in mathematics and other relevant subjects with respect to the delivery of statistics content and pedagogy. 2 Survey newly qualified teachers, trainee teachers and education lecturers about their attitudes to, and knowledge of teaching statistics. Objectives • Identify and catalogue mathematics teacher training courses and highlight those that pay attention to statistics knowledge and/or pedagogy; • Classify the entry profiles of students to such courses, particularly their statistics backgrounds; Objectives cont’d • Identify how the statistics content is delivered and the nature of the attention paid to statistical thinking and reasoning for teacher training courses in mathematics and other relevant subjects; • Identify and synthesise elements of good practice in statistics knowledge and pedagogy delivery within UK teacher training courses and disseminate findingsBackground • UK Government set up the post-14 Mathematics Inquir...
Australian & New Zealand Journal of Statistics, 2018
This study considers spatial dependence in the number of injury crashes reported on a road networ... more This study considers spatial dependence in the number of injury crashes reported on a road network. The aggregated crash counts are considered realisations of a Poisson random variable; thus, we model both over-dispersion and serial correlation using the Poisson hidden Markov model (PHMM). PHMMs have typically been used for modelling temporal dependence, but they have rarely been used to model spatial dependence. Our interest, however, is specifically in relation to an underlying point process which is constrained to occur on a network. We illustrate the use of the PHMM with police-reported data on injury road collisions on selected motorways in the United Kingdom over a 5-year period (2010-2014). We use officially recorded estimates of traffic volume as an exposure variable. The aim is to identify highway segments which might have distinctly high crash rates. To do this, we first select an optimal model in terms of the number of latent states. As we use a Bayesian approach, we can assign a posterior classification probability to each segment in terms of membership of the various underlying risk states. Model fitting is conducted using the Markov chain Monte Carlo approach; we develop a new modified version of the Akaike Information Criterion and Bayesian Information Criterion, approximated from a Bayesian framework, to select the best model in terms of number of states.
Journal of the Royal Statistical Society: Series A (Statistics in Society), 2016
In this book review, I offer a chapter-by-chapter recension and general comments about Richard Mc... more In this book review, I offer a chapter-by-chapter recension and general comments about Richard McElreath's second edition of Statistical Rethinking: A Bayesian Course with Examples in R and STAN. Two examples of linear regression modeling and the generalized linear model with the book's own R package rethinking highlight the flexibility and usefulness of considering the Bayesian approach to statistical modeling advertised by McElreath.
International Journal of Statistics and Probability, 2015
In Bayesian model selection, the deviance information criterion (DIC) has become a widely used cr... more In Bayesian model selection, the deviance information criterion (DIC) has become a widely used criterion. It is however not defined for the hidden Markov models (HMMs). In particular, the main challenge of applying the DIC for HMMs is that the observed likelihood function of such models is not available in closed form. A closed form for the observed likelihood function can be obtained either by summing all possible hidden states of the complete likelihood using the so-called the forward recursion, or via integrating out the hidden states in the conditional likelihood. Hence, we propose two versions of the DIC to the model choice problem in HMMs context, namely, the recursive deviance-based DIC and the conditional likelihood-based DIC. In this paper, we compare several normal HMMs after they are estimated by Bayesian MCMC method. We conduct a simulation study based on synthetic data generated under two assumptions, namely diversity in the heterogeneity level and also the number of st...
Journal of the Royal Statistical Society: Series D (The Statistician), 2003
Book reviews Books for review If you would like to review a book, and thereby to retain it for yo... more Book reviews Books for review If you would like to review a book, and thereby to retain it for your collection, please contact the Book Reviews Editor, whose details can be found by clicking on 'books currently available' in the information on the Royal Statistical Society's Web site:
To prospectively determine clinical and biochemical characteristics associated with the developme... more To prospectively determine clinical and biochemical characteristics associated with the development of peripheral neuropathy, loss of protective sensation, and foot ulceration in persons with type 2 diabetes mellitus (DM) over 7 years. Graded monofilament (MF) testing, vibration perception threshold, and neuropathy symptom questionnaires were undertaken in 206 participants with type 2 DM without peripheral vascular disease or history of foot ulceration and 71 healthy participants without DM at baseline and after 7 years. 6 monthly glycosylated hemoglobin (HbA1c) levels and annual serum lipid profiles were measured during follow-up of those with DM. Incident foot ulceration was recorded at follow-up. Taller stature and higher quartiles of serum triglyceride and HbA1c levels were associated with neuropathy at follow-up (p=0.008). Remission of baseline neuropathy was observed in 7 participants at follow-up. 9 participants with type 2 DM developed foot ulcers by the end of the study, on...
This webfile is designed as a revision aid to some introductory ideas on interval estimation. It ... more This webfile is designed as a revision aid to some introductory ideas on interval estimation. It is intended to supplement a formal encouter with a text book or a set of lectures. These notes are meant to be slightly interactive, mysterious green dots, squares and boxes appear which you can click on to answer questions and check solutions.
Promoting Understanding of Statistics about Society IASE Roundtable Conference
Many interesting social phenomena are innately multidimensional and require suitable data modelli... more Many interesting social phenomena are innately multidimensional and require suitable data modelling tools. Regression modelling (which includes log linear modelling for contingency tables as a special case) is often the „go-to'“ tool. However, much of the math theory was developed for designed experiments (where explanatory variables X are orthogonal and fixed). Conversely, societal data is often observational with random non-orthogonal X. The pedagogic route to data modelling usually starts with linear models before the introduction of the generalised linear models that can address contingency tables. Whilst good textbooks do feature caveats, the search for a parsimonious model is often carried out in a manner that may promote unsafe interpretation of observational data. This poster tries to present a case for a reform in the teaching of regression for observational data.
postgraduate and undergraduate teacher training courses in mathematics and other relevant subject... more postgraduate and undergraduate teacher training courses in mathematics and other relevant subjects with respect to the delivery of statistics content and pedagogy. 2 Survey newly qualified teachers, trainee teachers and education lecturers about their attitudes to, and knowledge of teaching statistics. Objectives • Identify and catalogue mathematics teacher training courses and highlight those that pay attention to statistics knowledge and/or pedagogy; • Classify the entry profiles of students to such courses, particularly their statistics backgrounds; Objectives cont’d • Identify how the statistics content is delivered and the nature of the attention paid to statistical thinking and reasoning for teacher training courses in mathematics and other relevant subjects; • Identify and synthesise elements of good practice in statistics knowledge and pedagogy delivery within UK teacher training courses and disseminate findingsBackground • UK Government set up the post-14 Mathematics Inquir...
Australian & New Zealand Journal of Statistics, 2018
This study considers spatial dependence in the number of injury crashes reported on a road networ... more This study considers spatial dependence in the number of injury crashes reported on a road network. The aggregated crash counts are considered realisations of a Poisson random variable; thus, we model both over-dispersion and serial correlation using the Poisson hidden Markov model (PHMM). PHMMs have typically been used for modelling temporal dependence, but they have rarely been used to model spatial dependence. Our interest, however, is specifically in relation to an underlying point process which is constrained to occur on a network. We illustrate the use of the PHMM with police-reported data on injury road collisions on selected motorways in the United Kingdom over a 5-year period (2010-2014). We use officially recorded estimates of traffic volume as an exposure variable. The aim is to identify highway segments which might have distinctly high crash rates. To do this, we first select an optimal model in terms of the number of latent states. As we use a Bayesian approach, we can assign a posterior classification probability to each segment in terms of membership of the various underlying risk states. Model fitting is conducted using the Markov chain Monte Carlo approach; we develop a new modified version of the Akaike Information Criterion and Bayesian Information Criterion, approximated from a Bayesian framework, to select the best model in terms of number of states.
Journal of the Royal Statistical Society: Series A (Statistics in Society), 2016
In this book review, I offer a chapter-by-chapter recension and general comments about Richard Mc... more In this book review, I offer a chapter-by-chapter recension and general comments about Richard McElreath's second edition of Statistical Rethinking: A Bayesian Course with Examples in R and STAN. Two examples of linear regression modeling and the generalized linear model with the book's own R package rethinking highlight the flexibility and usefulness of considering the Bayesian approach to statistical modeling advertised by McElreath.
International Journal of Statistics and Probability, 2015
In Bayesian model selection, the deviance information criterion (DIC) has become a widely used cr... more In Bayesian model selection, the deviance information criterion (DIC) has become a widely used criterion. It is however not defined for the hidden Markov models (HMMs). In particular, the main challenge of applying the DIC for HMMs is that the observed likelihood function of such models is not available in closed form. A closed form for the observed likelihood function can be obtained either by summing all possible hidden states of the complete likelihood using the so-called the forward recursion, or via integrating out the hidden states in the conditional likelihood. Hence, we propose two versions of the DIC to the model choice problem in HMMs context, namely, the recursive deviance-based DIC and the conditional likelihood-based DIC. In this paper, we compare several normal HMMs after they are estimated by Bayesian MCMC method. We conduct a simulation study based on synthetic data generated under two assumptions, namely diversity in the heterogeneity level and also the number of st...
Journal of the Royal Statistical Society: Series D (The Statistician), 2003
Book reviews Books for review If you would like to review a book, and thereby to retain it for yo... more Book reviews Books for review If you would like to review a book, and thereby to retain it for your collection, please contact the Book Reviews Editor, whose details can be found by clicking on 'books currently available' in the information on the Royal Statistical Society's Web site:
Uploads
Papers by Paul Hewson