scholarly journals Best (but oft-forgotten) practices: identifying and accounting for regression to the mean in nutrition and obesity research

2019 ◽  
Vol 111 (2) ◽  
pp. 256-265 ◽  
Author(s):  
Diana M Thomas ◽  
Nicholas Clark ◽  
Dusty Turner ◽  
Cynthia Siu ◽  
Tanya M Halliday ◽  
...  
Keyword(s):  
Best Practices ◽  
Repeated Measurements ◽  
Regression To The Mean ◽  
Intervention Effects ◽  
Measured Variable ◽  
Web Based ◽  
Obesity Research ◽  
Secondary Analyses ◽  
The Mean ◽  
Study Designs

ABSTRACT Background Regression to the mean (RTM) is a statistical phenomenon where initial measurements of a variable in a nonrandom sample at the extreme ends of a distribution tend to be closer to the mean upon a second measurement. Unfortunately, failing to account for the effects of RTM can lead to incorrect conclusions on the observed mean difference between the 2 repeated measurements in a nonrandom sample that is preferentially selected for deviating from the population mean of the measured variable in a particular direction. Study designs that are susceptible to misattributing RTM as intervention effects have been prevalent in nutrition and obesity research. This field often conducts secondary analyses of existing intervention data or evaluates intervention effects in those most at risk (i.e., those with observations at the extreme ends of a distribution). Objectives To provide best practices to avoid unsubstantiated conclusions as a result of ignoring RTM in nutrition and obesity research. Methods We outlined best practices for identifying whether RTM is likely to be leading to biased inferences, using a flowchart that is available as a web-based app at https://dustyturner.shinyapps.io/DecisionTreeMeanRegression/. We also provided multiple methods to quantify the degree of RTM. Results Investigators can adjust analyses to include the RTM effect, thereby plausibly removing its biasing influence on estimating the true intervention effect. Conclusions The identification of RTM and implementation of proper statistical practices will help advance the field by improving scientific rigor and the accuracy of conclusions. This trial was registered at clinicaltrials.gov as NCT00427193.

WHEN STUDY DESIGNS CONTROL FOR REGRESSION TO THE MEAN

2003 ◽  
Vol 35 (5) ◽  
pp. 887 ◽  
Author(s):  
W. Jack Rejeski ◽  
Lawrence R. Brawley ◽  
James L. Norris
Keyword(s):  
Regression To The Mean ◽  
The Mean ◽  
Study Designs

Regression to the Mean: A Commonly Overlooked and Misunderstood Factor Leading to Unjustified Conclusions in Pediatric Obesity Research

2016 ◽  
Vol 12 (2) ◽  
pp. 155-158 ◽  
Author(s):  
Asheley Cockrell Skinner ◽  
TaShauna U. Goldsby ◽  
David B. Allison
Keyword(s):  
Pediatric Obesity ◽  
Regression To The Mean ◽  
Obesity Research ◽  
The Mean

Kidney function decline is associated with an accelerated increase in plasma homocysteine in older adults: a longitudinal study

2021 ◽  
pp. 1-21
Author(s):  
Hui Zhang ◽  
Yi Li ◽  
Meng Hao ◽  
Xiaoyan Jiang ◽  
Jiucun Wang ◽  
...  
Keyword(s):  
Kidney Function ◽  
Repeated Measurements ◽  
Baseline Survey ◽  
Mixed Effect ◽  
Pronounced Increase ◽  
Crude Model ◽  
The Mean ◽  
Kidney Function Decline ◽  
Over Time

Abstract Background: Few studies have been conducted to investigate the association of kidney function decline with the trajectories of homocysteine (Hcy) over time, using repeated measurements. We aimed to investigate the association of kidney function with changes in plasma Hcy levels over time. Methods: Data were collected from the Rugao Longevity and Ageing Study. In detail, plasma Hcy and creatinine levels were measured in both waves (waves 2, 3 and 4) during the 3.5-year follow-up (N = 1135). Wave 2 was regarded as the baseline survey. The estimated glomerular filtration rate (eGFR) was calculated based on creatinine. Subjects were categorized into four groups according to quartiles of eGFR at baseline. Linear mixed-effect models were used to investigate the association of eGFR with subsequent plasma Hcy levels. Results: The mean eGFR at baseline was 90.84 (11.42) mL/min/1.73 m2. The mean plasma Hcy level was 14.09 (6.82) at baseline and increased to 16.28 (8.27) and 17.36 (10.39) μmol/L during follow-ups. In the crude model, the interaction between time and eGFR at baseline was significant (β = −0.02, 95% CI: −0.02 to −0.01, p = 0.002). After adjusting for confounding factors, a significant relationship remained (β = −0.02, 95% CI: −0.02 to −0.01, p = 0.003), suggesting that kidney function decline at baseline was associated with a faster increase in Hcy levels. Conclusion: Kidney function decline is associated with a more pronounced increase in plasma Hcy levels. Further studies with longer follow-up periods and larger sample sizes are needed to validate our findings.

scholarly journals Ketogenic Dietary Therapies in Patients with Autism Spectrum Disorder: Facts or Fads? A Scoping Review and a Proposal for a Shared Protocol

Nutrients ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 2057
Author(s):  
Costanza Varesio ◽  
Serena Grumi ◽  
Martina Paola Zanaboni ◽  
Martina Maria Mensi ◽  
Matteo Chiappedi ◽  
...  
Keyword(s):  
Autism Spectrum Disorder ◽  
Scoping Review ◽  
Pediatric Patients ◽  
Neurodevelopmental Disorder ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Dietary Interventions ◽  
Web Based ◽  
Potential Efficacy ◽  
Study Designs

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with increasing incidence. An expanding body of literature is examining connections between ASD and dietary interventions. Existing reports suggest a beneficial effect of ketogenic dietary therapies (KDTs) in improving behavioral symptoms in ASD. In this context, the purpose of this scoping review was to identify and map available evidence in the literature about the feasibility and potential efficacy of KDTs in pediatric patients with ASD and to inform clinical practice in the field. Moreover, based on the resulting data from the literature review, we aimed to provide a shared protocol to develop a personalized KDT intervention in patients with ASD. A comprehensive and structured web-based literature search was performed using PubMed and Scopus and it yielded 203 records. Seven papers were finally selected and included in the review. Data were abstracted by independent coders. High variability was identified in study designs and dietary aspects emerged among selected studies. Results supported the effectiveness of KDTs in promoting behavioral improvements. Clinical recommendations on which patients may benefit most from KDTs implementation and difficulties in dietary adherence were discussed.

Mines in the End Zone: Are there Downsides to Team Performance?

2020 ◽  
Vol 23 ◽  
Author(s):  
Troy V. Mumford ◽  
M. Travis Maynard
Keyword(s):  
Team Performance ◽  
Role Overload ◽  
Future Research ◽  
Negative Consequences ◽  
Regression To The Mean ◽  
Occupational Psychology ◽  
Team Success ◽  
The Mean ◽  
Overconfidence Bias

Abstract Research on teams in organizations tends to focus on understanding the causes of team performance with a focus on how to enjoy the benefits of team success and avoid the negative consequences of team failure. This paper instead asks the question, ‘what are some of the negative consequences of team success?’ A review of the literature on teams is augmented with research from cognitive science, sociology, occupational psychology, and psychology to explore the potential negative long-term consequences of teamwork success. The general topics of groupthink, overconfidence bias, regression to the mean, role overload, and strategy calcification are reviewed while discussing the implications for future research streams and practical team management.

scholarly journals Are the Effects of Homeopathy Attributable to a Statistical Artefact? A Reanalysis of an Observational Study

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Rainer Lüdtke ◽  
Stefan N. Willich ◽  
Thomas Ostermann
Keyword(s):  
Quality Of Life ◽  
Cohort Studies ◽  
Summary Score ◽  
Regression To The Mean ◽  
Sf 36 ◽  
The Mean ◽  
Component Scores ◽  
True Population ◽  
Respective Standard Deviation

Background. Cohort studies have reported that patients improve considerably after individualised homeopathic treatment. However, these results may be biased by regression to the mean (RTM).Objective. To evaluate whether the observed changes in previous cohort studies are due to RTM and to estimate RTM adjusted effects.Methods. SF-36 quality-of-life (QoL) data from a German cohort of 2827 chronically diseased adults treated by a homeopath were reanalysed by Mee and Chua’s modifiedt-test.Results. RTM adjusted effects, standardized by the respective standard deviation at baseline, were 0.12 (95% CI: 0.06–0.19,P<0.001) in the mental and 0.25 (0.22–0.28,P<0.001) in the physical summary score. Small-to-moderate effects were confirmed for the most individual diagnoses in physical, but not in mental component scores. Under the assumption that the true population mean equals the mean of all actually diseased patients, RTM adjusted effects were confirmed for both scores in most diagnoses.Conclusions. Changes in QoL after treatment by a homeopath are small but cannot be explained by RTM alone. As all analyses made conservative assumptions, true RTM adjusted effects are probably larger than presented.

Empirical methods for assessing meaningful neuropsychological change following epilepsy surgery

1996 ◽  
Vol 2 (6) ◽  
pp. 556-564 ◽  
Author(s):  
Stephen M. Sawrie ◽  
Gordon J. Chelune ◽  
Richard I. Naugle ◽  
Hans O. Lüders
Keyword(s):  
Epilepsy Surgery ◽  
Intractable Epilepsy ◽  
Practice Effects ◽  
Cutoff Score ◽  
Regression To The Mean ◽  
Neuropsychological Battery ◽  
Reliable Change ◽  
Medical Interventions ◽  
The Mean ◽  
Test Retest Reliability

AbstractTraditional methods for assessing the neurocognitive effects of epilepsy surgery are confounded by practice effects, test-retest reliability issues, and regression to the mean. This study employs 2 methods for assessing individual change that allow direct comparison of changes across both individuals and test measures. Fifty-one medically intractable epilepsy patients completed a comprehensive neuropsychological battery twice, approximately 8 months apart, prior to any invasive monitoring or surgical intervention. First, a Reliable Change (RC) index score was computed for each test score to take into account the reliability of that measure, and a cutoff score was empirically derived to establish the limits of statistically reliable change. These indices were subsequently adjusted for expected practice effects. The second approach used a regression technique to establish “change norms” along a common metric that models both expected practice effects and regression to the mean. The RC index scores provide the clinician with a statistical means of determining whether a patient's retest performance is “significantly” changed from baseline. The regression norms for change allow the clinician to evaluate the magnitude of a given patient's change on 1 or more variables along a common metric that takes into account the reliability and stability of each test measure. Case data illustrate how these methods provide an empirically grounded means for evaluating neurocognitive outcomes following medical interventions such as epilepsy surgery. (JINS, 1996, 2, 556–564.)

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