Summary The view is taken that statistical inference is a deductive process. Theories of inferen... more Summary The view is taken that statistical inference is a deductive process. Theories of inference then differ in the additives that are explicitly or implicitly added to the model and data. This focuses on the clear determination of the given for any inference analysis.
Open-cycle fuel cell development - space radiator optimization, techniques, mathematical models a... more Open-cycle fuel cell development - space radiator optimization, techniques, mathematical models and reliability
Concussion is the most common athletic injury in youth who are simultaneously undergoing rapid de... more Concussion is the most common athletic injury in youth who are simultaneously undergoing rapid developmental changes in the brain, specifically the development of executive functions (EF). The developing brain is more vulnerable to concussive injury with a protracted and different trajectory of recovery than that of adults. Thus, there is a critical need to enhance understanding of how concussion affects EF in youth. To investigate the effects of age, gender and concussion history (i.e. concussion incidence, recency, severity) on EF in youth hockey players. This 3-year cross-sectional and longitudinal multiple cohort study examined data from 211 hockey players of 8-15 years of age. Mixed-effects modelling was used to examine the influence of age, gender and concussion on EF in youth athletes. Baseline analyses revealed significant age and gender effects on measures of EF. Multiple effects of concussion history on measures of cognitive flexibility (F = 2.48, p = 0.03) and psychomotor speed (F = 2.59, p = 0.04) were found. This study highlights the impact of age, gender and concussion on EF in youth. These findings provide foundational knowledge to better manage cognitive sequelae following sports-related concussion.
Zeleis for various suggestions and contributions. Description This package accompanies J. Fox, An... more Zeleis for various suggestions and contributions. Description This package accompanies J. Fox, An R and S-PLUS Companion to Applied Regression, Sage, 2002. The package contains mostly functions for applied regression, linear models, and generalized linear models, with an emphasis on regression diagnostics, particularly graphical diagnostic methods. There are also some utility functions. With some exceptions, I have tried not to duplicate capabilities in the basic distribution of R, nor in widely used packages. Where relevant, the functions in car are consistent with na.action = na.omit or na.exclude.
Recent material is surveyed concerning the foundations of statistical models, the definition and ... more Recent material is surveyed concerning the foundations of statistical models, the definition and logic of statistical inference, and the additives used in various applications of theories of inference. This background is then used to compare structural/structured models [Fraser 1966, 1968, 1979] and pivotal models [Barnard 1974, 1981]; the models are found to be identical except for nomencalture and basic justification which supports the structural format. An outline is given of the development of the structural/structured model and of the corresponding mode of inference. The recent pivotal methods of analysis are assessed with this development as background.
Summary The view is taken that statistical inference is a deductive process. Theories of inferen... more Summary The view is taken that statistical inference is a deductive process. Theories of inference then differ in the additives that are explicitly or implicitly added to the model and data. This focuses on the clear determination of the given for any inference analysis.
International Journal of Sports Medicine, May 18, 2016
The objective of this study was to describe the effect of concussion on upper and lower body stre... more The objective of this study was to describe the effect of concussion on upper and lower body strength in children and youth athletes. The participant group was made up of 178 unique male and female ice hockey players (ages 8-14 years). Using a 3-year prospective longitudinal research design, baseline and post-concussion data on hand grip strength, jump tests, and leg maximal voluntary contraction were collected. Using a linear mixed-effects model, no significant differences were found when comparing the baseline strength performance of individuals who went on to experience a concussion and those who did not. When accounting for sex, multiple concussions, and ongoing changes in strength associated with age, weaker hand grip scores were found following concussion while participants were still symptomatic. Lower squat jump heights were achieved while participants were symptomatic as well as when they were no longer self-reporting symptoms associated with concussion. This study represents an initial step towards better understanding strength performance following concussion that may limit the on and off ice performance of youth ice hockey players, as well as predispose youth to subsequent injuries.
Concussion is the most common athletic injury in youth who are simultaneously undergoing rapid de... more Concussion is the most common athletic injury in youth who are simultaneously undergoing rapid developmental changes in the brain, specifically the development of executive functions (EF). The developing brain is more vulnerable to concussive injury with a protracted and different trajectory of recovery than that of adults. Thus, there is a critical need to enhance understanding of how concussion affects EF in youth. To investigate the effects of age, gender and concussion history (i.e. concussion incidence, recency, severity) on EF in youth hockey players. This 3-year cross-sectional and longitudinal multiple cohort study examined data from 211 hockey players of 8-15 years of age. Mixed-effects modelling was used to examine the influence of age, gender and concussion on EF in youth athletes. Baseline analyses revealed significant age and gender effects on measures of EF. Multiple effects of concussion history on measures of cognitive flexibility (F = 2.48, p = 0.03) and psychomotor speed (F = 2.59, p = 0.04) were found. This study highlights the impact of age, gender and concussion on EF in youth. These findings provide foundational knowledge to better manage cognitive sequelae following sports-related concussion.
The objective of this study was to describe the effect of concussion on upper and lower body stre... more The objective of this study was to describe the effect of concussion on upper and lower body strength in children and youth athletes. The participant group was made up of 178 unique male and female ice hockey players (ages 8-14 years). Using a 3-year prospective longitudinal research design, baseline and post-concussion data on hand grip strength, jump tests, and leg maximal voluntary contraction were collected. Using a linear mixed-effects model, no significant differences were found when comparing the baseline strength performance of individuals who went on to experience a concussion and those who did not. When accounting for sex, multiple concussions, and ongoing changes in strength associated with age, weaker hand grip scores were found following concussion while participants were still symptomatic. Lower squat jump heights were achieved while participants were symptomatic as well as when they were no longer self-reporting symptoms associated with concussion. This study represents an initial step towards better understanding strength performance following concussion that may limit the on and off ice performance of youth ice hockey players, as well as predispose youth to subsequent injuries.
Ancillary statistics, proposed by Fisher (1925), can be constructed by forming a mixture model (B... more Ancillary statistics, proposed by Fisher (1925), can be constructed by forming a mixture model (Birnbaum 1962) or can be extracted or derived from a transformation‐parameter model (Peisakoff 1951, Fraser 1961) or from the corresponding error‐based structural model (Fraser 1968, 1979); these latter models involve an implicit mixture structure. Compound models with ancillaries can also be formed by a cross embedding, discussed from a technical viewpoint in this paper. Of the 25 examples in Buehler (1982), 22 are mixtures or implicit mixtures and 3 correspond to cross embedding. The cross embedding examples exemplify the nonuniqueness difficulties with ancillaries. This paper discusses a simple and two generalized versions of cross embedding but makes no general valuations of these for statistical inference; their role within inference is discussed in Evans, Fraser, and Monette (1984, 1985).
Higher meaning in life (MIL) consistently predicts better health, but the physiological processes... more Higher meaning in life (MIL) consistently predicts better health, but the physiological processes underlying this relationship are not well understood. This study examined the relationship between MIL and vagally-mediated heart rate variability (VmHRV) under resting (N = 77), stressor (n = 73), and mindfulness intervention (n = 72) conditions. Regression was used for MIL-VmHRV analyses at baseline, and longitudinal mixed models were used to examine phasic changes in VmHRV as a function of MIL. Regression revealed a quadratic MIL-VmHRV relationship, and mixed models linked higher MIL to greater stress-reactivity but not enhanced stress-attenuation. MIL and mindfulness did not interact to influence VmHRV recovery after experimental stress. Findings suggest that cardiac vagal tone and cardiac vagal reactivity are linked to MIL, shedding light on the physiology underlying MIL and its health associations.
Antiretroviral therapy (ART) fails to fully restore immune function and is not curative. A single... more Antiretroviral therapy (ART) fails to fully restore immune function and is not curative. A single infusion of CCR5 gene-edited autologous CD4+ T cells (SB-728-T) led to sustained increases in CD4+ T cell counts, improved T cell homeostasis, and reduced the estimated size of the HIV reservoir. These outcomes were associated with the expansion and long-term persistence of a novel CCR5 gene-edited CD4+ T memory stem cell (CD45RAintROint TSCM) subset that can replenish the pool of more differentiated memory cells. We showed that novel CD45RAintROint TSCM cells are transcriptionally distinct from the previously described CD45RA+ TSCM and are minimally differentiated cells uncommitted to a specific Th-lineage. Subsequently, we showed in an independent trial that infusion of the SB-728-T cell product resulted in partial control of viral replication upon cessation of ART which was correlated with the frequencies of CCR5 gene-edited TSCM and their TEM progeny. Interestingly, one participant ...
Summary The view is taken that statistical inference is a deductive process. Theories of inferen... more Summary The view is taken that statistical inference is a deductive process. Theories of inference then differ in the additives that are explicitly or implicitly added to the model and data. This focuses on the clear determination of the given for any inference analysis.
Open-cycle fuel cell development - space radiator optimization, techniques, mathematical models a... more Open-cycle fuel cell development - space radiator optimization, techniques, mathematical models and reliability
Concussion is the most common athletic injury in youth who are simultaneously undergoing rapid de... more Concussion is the most common athletic injury in youth who are simultaneously undergoing rapid developmental changes in the brain, specifically the development of executive functions (EF). The developing brain is more vulnerable to concussive injury with a protracted and different trajectory of recovery than that of adults. Thus, there is a critical need to enhance understanding of how concussion affects EF in youth. To investigate the effects of age, gender and concussion history (i.e. concussion incidence, recency, severity) on EF in youth hockey players. This 3-year cross-sectional and longitudinal multiple cohort study examined data from 211 hockey players of 8-15 years of age. Mixed-effects modelling was used to examine the influence of age, gender and concussion on EF in youth athletes. Baseline analyses revealed significant age and gender effects on measures of EF. Multiple effects of concussion history on measures of cognitive flexibility (F = 2.48, p = 0.03) and psychomotor speed (F = 2.59, p = 0.04) were found. This study highlights the impact of age, gender and concussion on EF in youth. These findings provide foundational knowledge to better manage cognitive sequelae following sports-related concussion.
Zeleis for various suggestions and contributions. Description This package accompanies J. Fox, An... more Zeleis for various suggestions and contributions. Description This package accompanies J. Fox, An R and S-PLUS Companion to Applied Regression, Sage, 2002. The package contains mostly functions for applied regression, linear models, and generalized linear models, with an emphasis on regression diagnostics, particularly graphical diagnostic methods. There are also some utility functions. With some exceptions, I have tried not to duplicate capabilities in the basic distribution of R, nor in widely used packages. Where relevant, the functions in car are consistent with na.action = na.omit or na.exclude.
Recent material is surveyed concerning the foundations of statistical models, the definition and ... more Recent material is surveyed concerning the foundations of statistical models, the definition and logic of statistical inference, and the additives used in various applications of theories of inference. This background is then used to compare structural/structured models [Fraser 1966, 1968, 1979] and pivotal models [Barnard 1974, 1981]; the models are found to be identical except for nomencalture and basic justification which supports the structural format. An outline is given of the development of the structural/structured model and of the corresponding mode of inference. The recent pivotal methods of analysis are assessed with this development as background.
Summary The view is taken that statistical inference is a deductive process. Theories of inferen... more Summary The view is taken that statistical inference is a deductive process. Theories of inference then differ in the additives that are explicitly or implicitly added to the model and data. This focuses on the clear determination of the given for any inference analysis.
International Journal of Sports Medicine, May 18, 2016
The objective of this study was to describe the effect of concussion on upper and lower body stre... more The objective of this study was to describe the effect of concussion on upper and lower body strength in children and youth athletes. The participant group was made up of 178 unique male and female ice hockey players (ages 8-14 years). Using a 3-year prospective longitudinal research design, baseline and post-concussion data on hand grip strength, jump tests, and leg maximal voluntary contraction were collected. Using a linear mixed-effects model, no significant differences were found when comparing the baseline strength performance of individuals who went on to experience a concussion and those who did not. When accounting for sex, multiple concussions, and ongoing changes in strength associated with age, weaker hand grip scores were found following concussion while participants were still symptomatic. Lower squat jump heights were achieved while participants were symptomatic as well as when they were no longer self-reporting symptoms associated with concussion. This study represents an initial step towards better understanding strength performance following concussion that may limit the on and off ice performance of youth ice hockey players, as well as predispose youth to subsequent injuries.
Concussion is the most common athletic injury in youth who are simultaneously undergoing rapid de... more Concussion is the most common athletic injury in youth who are simultaneously undergoing rapid developmental changes in the brain, specifically the development of executive functions (EF). The developing brain is more vulnerable to concussive injury with a protracted and different trajectory of recovery than that of adults. Thus, there is a critical need to enhance understanding of how concussion affects EF in youth. To investigate the effects of age, gender and concussion history (i.e. concussion incidence, recency, severity) on EF in youth hockey players. This 3-year cross-sectional and longitudinal multiple cohort study examined data from 211 hockey players of 8-15 years of age. Mixed-effects modelling was used to examine the influence of age, gender and concussion on EF in youth athletes. Baseline analyses revealed significant age and gender effects on measures of EF. Multiple effects of concussion history on measures of cognitive flexibility (F = 2.48, p = 0.03) and psychomotor speed (F = 2.59, p = 0.04) were found. This study highlights the impact of age, gender and concussion on EF in youth. These findings provide foundational knowledge to better manage cognitive sequelae following sports-related concussion.
The objective of this study was to describe the effect of concussion on upper and lower body stre... more The objective of this study was to describe the effect of concussion on upper and lower body strength in children and youth athletes. The participant group was made up of 178 unique male and female ice hockey players (ages 8-14 years). Using a 3-year prospective longitudinal research design, baseline and post-concussion data on hand grip strength, jump tests, and leg maximal voluntary contraction were collected. Using a linear mixed-effects model, no significant differences were found when comparing the baseline strength performance of individuals who went on to experience a concussion and those who did not. When accounting for sex, multiple concussions, and ongoing changes in strength associated with age, weaker hand grip scores were found following concussion while participants were still symptomatic. Lower squat jump heights were achieved while participants were symptomatic as well as when they were no longer self-reporting symptoms associated with concussion. This study represents an initial step towards better understanding strength performance following concussion that may limit the on and off ice performance of youth ice hockey players, as well as predispose youth to subsequent injuries.
Ancillary statistics, proposed by Fisher (1925), can be constructed by forming a mixture model (B... more Ancillary statistics, proposed by Fisher (1925), can be constructed by forming a mixture model (Birnbaum 1962) or can be extracted or derived from a transformation‐parameter model (Peisakoff 1951, Fraser 1961) or from the corresponding error‐based structural model (Fraser 1968, 1979); these latter models involve an implicit mixture structure. Compound models with ancillaries can also be formed by a cross embedding, discussed from a technical viewpoint in this paper. Of the 25 examples in Buehler (1982), 22 are mixtures or implicit mixtures and 3 correspond to cross embedding. The cross embedding examples exemplify the nonuniqueness difficulties with ancillaries. This paper discusses a simple and two generalized versions of cross embedding but makes no general valuations of these for statistical inference; their role within inference is discussed in Evans, Fraser, and Monette (1984, 1985).
Higher meaning in life (MIL) consistently predicts better health, but the physiological processes... more Higher meaning in life (MIL) consistently predicts better health, but the physiological processes underlying this relationship are not well understood. This study examined the relationship between MIL and vagally-mediated heart rate variability (VmHRV) under resting (N = 77), stressor (n = 73), and mindfulness intervention (n = 72) conditions. Regression was used for MIL-VmHRV analyses at baseline, and longitudinal mixed models were used to examine phasic changes in VmHRV as a function of MIL. Regression revealed a quadratic MIL-VmHRV relationship, and mixed models linked higher MIL to greater stress-reactivity but not enhanced stress-attenuation. MIL and mindfulness did not interact to influence VmHRV recovery after experimental stress. Findings suggest that cardiac vagal tone and cardiac vagal reactivity are linked to MIL, shedding light on the physiology underlying MIL and its health associations.
Antiretroviral therapy (ART) fails to fully restore immune function and is not curative. A single... more Antiretroviral therapy (ART) fails to fully restore immune function and is not curative. A single infusion of CCR5 gene-edited autologous CD4+ T cells (SB-728-T) led to sustained increases in CD4+ T cell counts, improved T cell homeostasis, and reduced the estimated size of the HIV reservoir. These outcomes were associated with the expansion and long-term persistence of a novel CCR5 gene-edited CD4+ T memory stem cell (CD45RAintROint TSCM) subset that can replenish the pool of more differentiated memory cells. We showed that novel CD45RAintROint TSCM cells are transcriptionally distinct from the previously described CD45RA+ TSCM and are minimally differentiated cells uncommitted to a specific Th-lineage. Subsequently, we showed in an independent trial that infusion of the SB-728-T cell product resulted in partial control of viral replication upon cessation of ART which was correlated with the frequencies of CCR5 gene-edited TSCM and their TEM progeny. Interestingly, one participant ...
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