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"Alston, Clair"
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Accreditation of new technologies for predicting intramuscular fat percentage: Combining Bayesian models and industry rules for transparent decisions
2025
The experiment evaluated a method for statistically assessing the accuracy of technologies that measure intramuscular fat percentage (IMF%), enabling referencing against accreditation accuracy thresholds. To compare this method to the existing rules-based industry standard we simulated data for 4 separate devices that predicted IMF% across a range between 0.5–9.5% for sheep meat. These devices were simulated to reflect increasingly inaccurate predictions, and the two methods for statistically assessing accuracy were then applied. We found that for the technology which only just meets the accreditation accuracy standards, as few as 25 samples were required within each quarter of the IMF% range to achieve 80% likelihood of passing accreditation. In contrast, using the rules based approach at least 200 samples were required within each quarter of the IMF% range, and this increased the likelihood of passing to only 50%. This method has been developed into an on-line analysis App, which commercial users can freely access to test the accuracy of their technologies.
Journal Article
Non-significant p-values? Strategies to understand and better determine the importance of effects and interactions in logistic regression
2018
In the context of generalized linear models (GLMs), interactions are automatically induced on the natural scale of the data. The conventional approach to measuring effects in GLMs based on significance testing (e.g. the Wald test or using deviance to assess model fit) is not always appropriate. The objective of this paper is to demonstrate the limitations of these conventional approaches and to explore alternative strategies for determining the importance of effects. The paper compares four approaches to determining the importance of effects in the GLM using 1) the Wald statistic, 2) change in deviance (model fitting criteria), 3) Bayesian GLM using vaguely informative priors and 4) Bayesian Model Averaging analysis. The main points in this paper are illustrated using an example study, which examines the risk factors for cyber abuse victimization, and are further examined using a simulation study. Analysis of our example dataset shows that, in terms of a logistic GLM, the conventional methods using the Wald test and the change in deviance can produce results that are difficult to interpret; Bayesian analysis of GLM is a suitable alternative, which is enhanced with prior knowledge about the direction of the effects; and Bayesian Model Averaging (BMA) is especially suited for new areas of research, particularly in the absence of theory. We recommend that social scientists consider including BMA in their standard toolbox for analysis of GLMs.
Journal Article
Exploring the Sensory Profiles of Children on the Autism Spectrum Using the Short Sensory Profile-2 (SSP-2)
2019
The aim of this study was to identify sensory subtypes in children on the autism spectrum using the Short Sensory Profile-2 (SSP-2). Caregivers of children on the autism spectrum aged 4–11 years (
n
= 271) completed the SSP-2. Analysis using Dirichlet process mixture model identified a two-cluster model which provided the best solution to subtype sensory responses. Two distinct subtypes were identified: Uniformly elevated (67%) with high scores across all quadrants and Raised avoiding and sensitivity (33%) with raised scores in the avoiding and sensitivity quadrants. There were no differences between subtypes based on chronological age and autism characteristics measured using the social communication questionnaire (total score). Based on the SSP-2, children were reported to experience differences in responses to sensory input, in particular in the area of sensitivity and avoiding.
Journal Article
Classroom management practices commonly used by secondary school teachers : results from a Queensland survey
by
Wendi Beamish
,
Lorna Hepburn
,
Clair L. Alston-Knox
in
Beginning Teachers
,
Behavior
,
Behavior Problems
2021
A preventative approach to classroom management is associated with increases in student engagement and improved teacher well-being. However, research indicates that many teachers use predominantly reactive practices, aimed at controlling student behaviour. Queensland state secondary school teachers (N = 587) were surveyed about the classroom management practices they most often used to prevent and respond to unproductive student behaviours in their classrooms. Findings indicated that teachers mainly relied on practices to establish expectations, practices from the Essential Skills for Classroom Management professional development resource, and practices which sanction students for behavioural infractions. There were, however, also encouraging indications that teachers try to prevent unproductive behaviour by fostering student engagement in learning activities while addressing misbehaviour in low-key ways. Implications for pre-service teacher preparation and ongoing professional development are discussed. [Author abstract]
Journal Article
Case studies in Bayesian statistical modelling and analysis
by
Alston, Clair L.
,
Mengersen, Kerrie L.
,
Pettitt, A. N.
in
Bayesian statistical decision theory
,
MATHEMATICS
,
Statistical decision
2013,2012
Provides an accessible foundation to Bayesian analysis using real world models
This book aims to present an introduction to Bayesian modelling and computation, by considering real case studies drawn from diverse fields spanning ecology, health, genetics and finance. Each chapter comprises a description of the problem, the corresponding model, the computational method, results and inferences as well as the issues that arise in the implementation of these approaches.
Case Studies in Bayesian Statistical Modelling and Analysis:
* Illustrates how to do Bayesian analysis in a clear and concise manner using real-world problems.
* Each chapter focuses on a real-world problem and describes the way in which the problem may be analysed using Bayesian methods.
* Features approaches that can be used in a wide area of application, such as, health, the environment, genetics, information science, medicine, biology, industry and remote sensing.
Case Studies in Bayesian Statistical Modelling and Analysis is aimed at statisticians, researchers and practitioners who have some expertise in statistical modelling and analysis, and some understanding of the basics of Bayesian statistics, but little experience in its application. Graduate students of statistics and biostatistics will also find this book beneficial.
To SPB or not to SPB? A mixed methods analysis of self-protective behaviours to prevent repeat victimisation from cyber abuse
by
Stephens, Callum A
,
Vakhitova, Zarina I
,
Alston-Knox, Clair L
in
Adults
,
Bayesian analysis
,
Cyberbullying
2020
This paper presents the findings from a mixed-methods examination of self-protective behaviours (SPBs) adopted by victims of cyber abuse from the rational choice perspective. The data from a sample of the U.S. adults (N=746), members of an online opt-in panel, were analysed to first distinguish the types of SPBs adopted by victims of cyber abuse using a thematic analysis of open-ended responses. We then identified the factors associated with an increased likelihood of adopting SPBs and the specific identified types of SPBs using logistic regression with Bayesian variable selection and a stochastic search algorithm. Of the six identified types of SPBs, adjusting privacy settings was the most commonly reported response, and improving security (e.g. changing passwords, etc.) was the least common SPB. Older victims who reported higher than the average perceived impact from victimisation, were abused by a stranger and experienced either surveillance of their online activities or multiple types of abuse, were significantly more likely to adopt an SPB. Our findings inform strategies for both Internet user education and for preventing cyber abuse victimisation.
Journal Article
Sire Breed, Litter Size, and Environment Influence Genetic Potential for Lamb Growth When Using Sire Breeding Values
by
Gardner, Graham E.
,
Kelman, Khama R.
,
Pethick, David W.
in
Birth weight
,
breeding value
,
cooperative research
2022
Lamb growth can be optimised with genetic selection using sire Australian sheep breeding values, however, breeding value expression has been shown to be reduced with poor nutrition. It was therefore hypothesised that the genetic potential for lamb growth would also be reduced, where production factors such as multiple births limit growth. Live weights at birth, weaning, and post-weaning were collected from more than 18,000 lambs produced over five years and eight locations of the Sheep Cooperative Research Centre Information Nucleus Flock experiment, and the impact of environment, production factors, and genotype was determined using mixed effects regression. The genetic potential for lamb growth was moderated by environment, multiple births, and sire type (p < 0.05). Twin lambs achieved 76% of the expected weight gain at weaning and 58% post-weaning. For triplet lambs weight gains were drastically less at approximately 30% of the expected gain at the same time points. Lambs born to maternal sires consistently had the poorest response to genetic selection, achieving approximately half the expected weight gain. Hence, producers need to temper expectations for growth based on genetic selection, or employ mitigation strategies such as precision feeding, the use of alternate breeds, or place emphasis on the genetic merit of other desirable traits.
Journal Article
D‐cycloserine‐augmented one‐session treatment of specific phobias in children and adolescents
by
Alston‐Knox, Clair
,
Storch, Eric A.
,
Tiralongo, Evelin
in
Adolescent
,
Adult
,
Anti-Anxiety Agents - administration & dosage
2018
Background D‐Cycloserine has potential to enhance exposure therapy outcomes. The current study presents a preliminary randomized, placebo‐controlled double‐blind pilot trial of DCS‐augmented one‐session treatment (OST) for youth (7–14 years) with specific phobia. A secondary aim of this pilot study was to explore the effects of youth age and within‐session fear reduction as potential moderators of DCS outcomes in order to generate hypotheses for a larger trial. It was hypothesized that DCS would be associated with greater improvements than placebo, that children (7–10 years) would have greater benefits than adolescents (11–14 years), and that DCS effects would be stronger for participants with the greater within‐session fear reduction during the OST. Methods Thirty‐five children and adolescents were randomized to either OST combined with DCS (n = 17), or OST combined with placebo (PBO; n = 18) and assessed at 1 week, 1 month, and 3 month following treatment. Results There were no significant pre‐ to post‐treatment or follow‐up benefits of DCS relative to placebo. Secondary analyses of age indicated that relative to PBO, DCS was associated with greater improvements for children (but not adolescents) on measures of severity at 1‐month follow‐up. Children in the DCS condition also showed significantly greater improvement to 1 month on global functioning relative to other groups. Conversely, adolescents had significant post‐treatment benefits in the PBO condition on symptom severity measures relative to DCS, and adolescents in the DCS condition had significantly poorer functioning at 3 months relative to all other groups. Finally, there was a trend for within‐session fear reduction to be associated with moderating effects of DCS, whereby greater reduction in fear was associated with greater functioning at one‐month follow‐up for children who received DCS, relative to PBO. Limitations The study sample was small and therefore conclusions are tentative and require replication. Conclusions Age and within‐session fear reduction may be important moderators of DCS‐augmented one‐session exposure therapy, which requires testing in a fully powered randomized controlled trial. d‐Cycloserine (DCS), an antituberculosis antibiotic, has been found to enhance exposure therapy outcomes for children and adults with various anxiety disorders; however, results of trials to date have been mixed. The efficacy of DCS in augmenting a single‐session exposure treatment for children and adolescents with specific phobia was evaluated in a preliminary double‐blind randomised controlled trial. DCS was not found to be superior to placebo for the overall sample; however, secondary analyses found that DCS was associated with positive augmenting effects for younger children, but not older, and moreover, within‐session fear reduction may moderate outcomes of DCS, with greater reduction in fear during the single session associated with a trend toward superior functioning one month later for younger children, but not older children.
Journal Article
Using Bayesian methodology to explore the profile of mental health and well-being in 646 mothers of children with 13 rare genetic syndromes in relation to mothers of children with autism
2018
Background
It is well documented that mothers of children with intellectual disabilities or autism experience elevated stress, with mental health compromised. However, comparatively little is known about mothers of children with rare genetic syndromes. This study describes mental health and well-being in mothers of children with 13 rare genetic syndromes and contrasts the results with mothers of children with autism.
Methods
Mothers of children with 13 genetic syndromes (
n
= 646; Angelman, Cornelia de Lange, Down, Fragile-X, Phelan McDermid, Prader-Willi, Rett, Rubenstein Taybi, Smith Magenis, Soto, Tuberous Sclerosis Complex, 1p36 deletion and 8p23 deletion syndromes) and mothers of children with autism (
n
= 66) completed measures of positive mental health, stress and depression. Using Bayesian methodology, the influence of syndrome, child ability, and mother and child age were explored in relation to each outcome. Bayesian Model Averaging was used to explore maternal depression, positive gain and positive affect, and maternal stress was tested using an ordinal probit regression model.
Results
Different child and mother factors influenced different aspects of mental well-being, and critically, the importance of these factors differed between syndromes. Maternal depression was influenced by child ability in only four syndromes, with the other syndromes reporting elevated or lower levels of maternal depression regardless of child factors. Maternal stress showed a more complex pattern of interaction with child ability, and for some groups, child age. Within positive mental health, mother and child age were more influential than child ability. Some syndromes reported comparable levels of depression (SMS, 1p36, CdLS) and stress (SMS, AS) to mothers of children with autism.
Conclusions
Bayesian methodology was used in a novel manner to explore factors that explain variability in mental health amongst mothers of children with rare genetic disorders. Significant proportions of mothers of children with specific genetic syndromes experienced levels of depression and stress similar to those reported by mothers of children with autism. Identifying such high-risk mothers allows for potential early intervention and the implementation of support structures.
Journal Article