Explorations in statistics: the analysis of change

Curran‐Everett, Douglas; Williams, Calvin L.

doi:10.1152/advan.00018.2015

Cited by 31 publications

(24 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The advantage of any index is that it consolidates lots of complex information into a single number (13), but this is also the disadvantage (23). Indeed, EF is a tricky index, similar to all other dimensionless ratios, which can wreak havoc and mislead us (4). This fact is illustrated in Fig.…”

Section: The Pv Loop and The Starling Curvementioning

confidence: 90%

Left ventricular volume analysis as a basic tool to describe cardiac function

Kerkhof¹,

Kuznetsova

Ali³

et al. 2018

Advances in Physiology Education

View full text Add to dashboard Cite

The heart is often regarded as a compression pump. Therefore, determination of pressure and volume is essential for cardiac function analysis. Traditionally, ventricular performance was described in terms of the Starling curve, i.e., output related to input. This view is based on two variables (namely, stroke volume and end-diastolic volume), often studied in the isolated (i.e., denervated) heart, and has dominated the interpretation of cardiac mechanics over the last century. The ratio of the prevailing coordinates within that paradigm is termed ejection fraction (EF), which is the popular metric routinely used in the clinic. Here we present an insightful alternative approach while describing volume regulation by relating end-systolic volume (ESV) to end-diastolic volume. This route obviates the undesired use of metrics derived from differences or ratios, as employed in previous models. We illustrate basic principles concerning ventricular volume regulation by data obtained from intact animal experiments and collected in healthy humans. Special attention is given to sex-specific differences. The method can be applied to the dynamics of a single heart and to an ensemble of individuals. Group analysis allows for stratification regarding sex, age, medication, and additional clinically relevant covariates. A straightforward procedure derives the relationship between EF and ESV and describes myocardial oxygen consumption in terms of ESV. This representation enhances insight and reduces the impact of the metric EF, in favor of the end-systolic elastance concept advanced 4 decades ago.

show abstract

Section: The Pv Loop and The Starling Curvementioning

confidence: 90%

Left ventricular volume analysis as a basic tool to describe cardiac function

Kerkhof¹,

Kuznetsova

Ali³

et al. 2018

Advances in Physiology Education

View full text Add to dashboard Cite

show abstract

“…Both have their place yet one can argue that change scores can create a bias towards the group with poorer baseline scores. In this scenario, consideration should be given adjusting data relative to potential confounding issues [24]. With respect to reporting, however, the CONSORT guidelines promote the use of confidence intervals [13].…”

Section: Discussionmentioning

confidence: 99%

Reporting Characteristics in Sports Nutrition

Earnest

Roberts

Harnish

et al. 2018

Sports

View full text Add to dashboard Cite

Purpose: To examine data reporting characteristics in sports nutrition. Methods: We examined 236 papers from ten journals published in 2016. The primary outcome was statistical variance associated with treatment (SD (correct) vs. SEM or CI). Secondary outcomes included the reporting of: (a) effect sizes (Y/N); (b) outcome prioritization (Y/N; primary, secondary, etc.) and (c) statistical variance relative to change from baseline (CI (correct) vs. SD or SEM). As tertiary/exploratory outcome, we examined whether authors stated a directed hypothesis. Statistical evaluation was performed using chi-square analyses. Results: We observed significant trends for all analyses (p < 0.001) and between category comparisons (p < 0.002). For the primary outcome, 128 (59%) articles correctly used SD to denote treatment variance, while 79 (36%) and 11 (5%) used SEM and CI, respectively. For secondary outcomes, 63 articles (29%) reported effect sizes, while 155 (71%) did not. Additionally, 188 articles (86%) did not prioritize outcomes, 134 articles (61%) stated no hypotheses and 40 (19%, out of 100) articles used CI to denote change scores vs. SD (19%, n = 41) and SEM (n = 10, 5%). Eight articles (4%) reported no variance terms. Conclusions: Overall, there are gaps regarding reporting in sports nutrition. Editors, journal publishers, and the field of exercise science alike should consider these outcomes and provide editorial staff, reviewers and authors with more concrete guidelines.

show abstract

“…Data in the figures show per cent changes. We did not perform statistical analyses on these data, as per cent changes are just ratios, and, therefore, may lead to misleading results . Thus, we performed statistical analyses using the raw data, while the figures presenting the per cent changes were used complementarily in order to better illustrate the findings of the study.…”

Section: Methodsmentioning

confidence: 99%

Adaptations to endurance training depend on exercise‐induced oxidative stress: exploiting redox interindividual variability

et al. 2017

View full text Add to dashboard Cite

Aim: The aim of this study was to reveal the role of reactive oxygen and nitrogen species (RONS) in exercise adaptations under physiological in vivo conditions and without the interference from other exogenous redox agents (e.g. a pro-oxidant or antioxidant). Methods: We invented a novel methodological set-up that exploited the large redox interindividual variability in exercise responses. More specifically, we used exercise-induced oxidative stress as the 'classifier' measure (i.e. low, moderate and high) and investigated the physiological and redox adaptations after a 6-week endurance training protocol. Results: We demonstrated that the group with the low exercise-induced oxidative stress exhibited the lowest improvements in a battery of classic adaptations to endurance training (VO 2 max, time trial and Wingate test) as well as in a set of redox biomarkers (oxidative stress biomarkers and antioxidants), compared to the high and moderate oxidative stress groups. Conclusion: The findings of this study substantiate, for the first time in a human in vivo physiological context, and in the absence of any exogenous redox manipulation, the vital role of RONS produced during exercise in adaptations. The stratification approach, based on a redox phenotype, implemented in this study could be a useful experimental strategy to reveal the role of RONS and antioxidants in other biological manifestations as well.

show abstract

Explorations in statistics: the analysis of change

Cited by 31 publications

References 19 publications

Left ventricular volume analysis as a basic tool to describe cardiac function

Left ventricular volume analysis as a basic tool to describe cardiac function

Reporting Characteristics in Sports Nutrition

Adaptations to endurance training depend on exercise‐induced oxidative stress: exploiting redox interindividual variability

Contact Info

Product

Resources

About