scholarly journals Statistical limitations on drawing inferences about proportional recovery

2019 ◽  
Author(s):  
Keith R. Lohse ◽  
Rachel Hawe ◽  
Sean Dukelow ◽  
Stephen H. Scott
Keyword(s):  
Population Level ◽  
Significance Test ◽  
Current Evidence ◽  
Biological Phenomenon ◽  
Change Scores ◽  
Level Statistic ◽  
Cast Doubt ◽  
Alternative Hypotheses ◽  
Statistical Relationships ◽  
Mathematical Coupling

AbstractBackgroundNumerous studies have found large statistical relationships between the amount of recovery and initial impairments in people with stroke. When change scores are regressed onto initial impairments, the resulting slope is approximately ≈0.7for a variety of outcomes. These findings have led to the 70% “proportional recovery rule” and the argument that proportional recovery represents a biological phenomenon. Previous studies of proportional recovery are confounded by statistical limitations that come from regressing change scores onto initial impairments in bounded scales.ObjectiveOur goal is to show that data claimed as evidence for proportional recovery are generally consistent with random patterns of recovery, once statistical limitations are taken into account.MethodsUsing a pooled dataset of N = 373 Fugl-Meyer Assessment (FMA) upper extremity scores extracted from published literature, we ran simulations to illustrate three main arguments: (1) Mathematical coupling renders the traditional null-hypothesis significance test irrelevant in proportional recovery studies; (2) Proportional recovery is one of many alternative hypotheses; (3) Current evidence claimed in favor of proportional recovery is consistent with uniform random recovery.ResultsOur simulations show that if all data were included (no exclusion of “non-fitters”) regressing change scores onto initial impairments in a bounded scale would lead to a slope of ≈ 0.5. Similarly, cluster analysis will spuriously identify groups of fitters and non-fitters, leading to a slope for the fitters of ≈ 0.7, when the underlying recovery is random.ConclusionsThese results cast doubt on the validity of “proportional recovery” as a population level-statistic and a biological phenomenon.

scholarly journals Information-based taste maps in insular cortex are shaped by stimulus concentration

2019 ◽  
Author(s):  
E Porcu ◽  
KM Benz ◽  
F Ball ◽  
C Tempelmann ◽  
M Hanke ◽  
...  
Keyword(s):  
Complex Function ◽  
Insular Cortex ◽  
Population Level ◽  
Ingestive Behavior ◽  
Current Evidence ◽  
High Concentration ◽  
Potential Harm ◽  
Taste Processing ◽  
Human Participants ◽  
Multivariate Pattern

AbstractTaste processing is an essential ability in all animals signaling potential harm or benefit of ingestive behavior. Although the peripheral taste coding is well understood, current evidence for central taste processing remains contradictory. To address this issue, human participants judged pleasantness and intensity of low and high-concentration tastes (salty, sweet, sour, bitter) in two fMRI-experiments. High-resolution fMRI and multivariate pattern analysis were used to characterize taste-related informational content in human gustatory cortex (GC). Clusters within GC were narrowly tuned to specific tastants consistently across tasks. Importantly, taste concentrations completely altered the spatial layout of putative taste-specific maps with distinct, non-overlapping patterns for each taste category at different concentration levels. Together, our results point at population-level representations in human GC as a complex function of taste category and concentration.

scholarly journals How fast is fast enough? Walking cadence (steps/min) as a practical estimate of intensity in adults: a narrative review

2018 ◽  
Vol 52 (12) ◽  
pp. 776-788 ◽  
Author(s):  
Catrine Tudor-Locke ◽  
Ho Han ◽  
Elroy J Aguiar ◽  
Tiago V Barreira ◽  
John M Schuna Jr ◽  
...  
Keyword(s):  
Population Level ◽  
Strong Relationship ◽  
Epidemiological Studies ◽  
Moderate Intensity ◽  
Current Evidence ◽  
Free Living ◽  
Metabolic Equivalents ◽  
Registration Number ◽  
Comprehensive Search ◽  
Comprehensive Search Strategy

BackgroundCadence (steps/min) may be a reasonable proxy-indicator of ambulatory intensity. A summary of current evidence is needed for cadence-based metrics supporting benchmark (standard or point of reference) and threshold (minimums associated with desired outcomes) values that are informed by a systematic process.ObjectiveTo review how fast, in terms of cadence, is enough, with reference to crafting public health recommendations in adults.MethodsA comprehensive search strategy was conducted to identify relevant studies focused on walking cadence and intensity for adults. Identified studies (n=38) included controlled (n=11), free-living observational (n=18) and intervention (n=9) designs.ResultsThere was a strong relationship between cadence (as measured by direct observation and objective assessments) and intensity (indirect calorimetry). Despite acknowledged interindividual variability, ≥100 steps/min is a consistent heuristic (e.g, evidence-based, rounded) value associated with absolutely defined moderate intensity (3 metabolic equivalents (METs)). Epidemiological studies report notably low mean daily cadences (ie, 7.7 steps/min), shaped primarily by the very large proportion of time (13.5 hours/day) spent between zero and purposeful cadences (<60 steps/min) at the population level. Published values for peak 1-min and 30-min cadences in healthy free-living adults are >100 and >70 steps/min, respectively. Peak cadence indicators are negatively associated with increased age and body mass index. Identified intervention studies used cadence to either prescribe and/or quantify ambulatory intensity but the evidence is best described as preliminary.ConclusionsA cadence value of ≥100 steps/min in adults appears to be a consistent and reasonable heuristic answer to ’How fast is fast enough?' during sustained and rhythmic ambulatory behaviour.Trial registration numberNCT02650258

The null-hypothesis significance-test procedure is still warranted

1998 ◽  
Vol 21 (2) ◽  
pp. 228-235 ◽  
Author(s):  
Siu L. Chow
Keyword(s):  
Null Hypothesis ◽  
Statistical Power ◽  
Meta Analysis ◽  
Statistical Significance ◽  
Test Procedure ◽  
Significance Test ◽  
Null Hypothesis Significance Test ◽  
Wide Range ◽  
Statistical Hypotheses ◽  
Alternative Hypotheses

Entertaining diverse assumptions about empirical research, commentators give a wide range of verdicts on the NHSTP defence in Statistical significance. The null-hypothesis significance-test procedure (NHSTP) is defended in a framework in which deductive and inductive rules are deployed in theory corroboration in the spirit of Popper's Conjectures and refutations (1968b). The defensible hypothetico-deductive structure of the framework is used to make explicit the distinctions between (1) substantive and statistical hypotheses, (2) statistical alternative and conceptual alternative hypotheses, and (3) making statistical decisions and drawing theoretical conclusions. These distinctions make it easier to show that (1) H0 can be true, (2) the effect size is irrelevant to theory corroboration, and (3) “strong” hypotheses make no difference to NHSTP. Reservations about statistical power, meta-analysis, and the Bayesian approach are still warranted.

scholarly journals Antimicrobial Resistance Following Azithromycin Mass Drug Administration: Potential Surveillance Strategies to Assess Public Health Impact

2019 ◽  
Vol 70 (7) ◽  
pp. 1501-1508 ◽  
Author(s):  
Ines Mack ◽  
Mike Sharland ◽  
James A Berkley ◽  
Nigel Klein ◽  
Surbhi Malhotra-Kumar ◽  
...  
Keyword(s):  
Drug Administration ◽  
Mass Drug Administration ◽  
Controlled Trial ◽  
Population Level ◽  
Health Impact ◽  
Childhood Mortality ◽  
World Health ◽  
Current Evidence ◽  
Multiresistant Pathogens ◽  
Microbiological Techniques

Abstract The reduction in childhood mortality noted in trials investigating azithromycin mass drug administration (MDA) for trachoma control has been confirmed by a recent large randomized controlled trial. Population-level implementation of azithromycin MDA may lead to selection of multiresistant pathogens. Evidence suggests that repeated azithromycin MDA may result in a sustained increase in macrolide and other antibiotic resistance in gut and respiratory bacteria. Current evidence comes from standard microbiological techniques in studies focused on a time-limited intervention, while MDA implemented for mortality benefits would likely repeatedly expose the population over a prolonged period and may require a different surveillance approach. Targeted short-term and long-term surveillance of resistance emergence to key antibiotics, especially those from the World Health Organization Access group, is needed throughout any implementation of azithromycin MDA, focusing on a genotypic approach to overcome the limitations of resistance surveillance in indicator bacteria.

scholarly journals Evidence Based Surgical Approach to Locally Advanced Gastric Cancer

2019 ◽  
Vol 17 (2) ◽  
pp. 133-140
Author(s):  
Binay Thakur ◽  
Mukti Devkota ◽  
Amit Sharma ◽  
Manish Chaudhary
Keyword(s):  
Gastric Cancer ◽  
Soviet Union ◽  
Advanced Gastric Cancer ◽  
Former Soviet Union ◽  
Locally Advanced ◽  
Population Level ◽  
Multimodality Treatment ◽  
Current Evidence ◽  
Curative Surgery ◽  
Locally Advanced Gastric Cancer

Gastric cancer is endemic in China, Japan, Korea, Brazil and Former Soviet Union. Patients are diagnosed usually in locally advanced stage. Endoscopy, Positron Emission Therapy- Computed Tomography, Endoscopic ultrasound and staging laparoscopy are the tools for proper evaluation of such patients. Locally advanced gastric cancer (T2-4N0 or TanyN+) requires multimodality treatment including surgery. Resection is the cornerstone of cure for gastric adenocarcinoma; however, several aspects of surgical intervention remain controversial or are suboptimally applied at a population level. Current evidence shows a D2 gastrectomy has got the best survival results. At least 15 lymph nodes should be assessed for adequate staging. Laparoscopic resections should be performed to the same standards as those for for open resections, by surgeons who are experienced in both advanced laparoscopic surgery and gastric cancer management.Keywords: Curative surgery; gastrectomy; stomach neoplasms.

forming an asymmetrical brain: genes, environment, and evolutionarily stable strategies

2005 ◽  
Vol 28 (4) ◽  
pp. 615-623 ◽  
Author(s):  
giorgio vallortigara ◽  
lesley j. rogers
Keyword(s):  
Evolutionarily Stable Strategy ◽  
Population Level ◽  
Brain Lateralization ◽  
Evolutionarily Stable Strategies ◽  
Evolutionary Account ◽  
Advantages And Disadvantages ◽  
Alternative Hypotheses ◽  
The Individual ◽  
Present Response ◽  
Evolutionarily Stable

the present response elaborates and defends the main theses advanced in the target article: namely, that in order to provide an evolutionary account of brain lateralization, we should consider advantages and disadvantages associated both with the individual possession of an asymmetrical brain and with the alignment of the direction of lateralization at the population level. we explain why we believe that the hypothesis that directional lateralization evolved as an evolutionarily stable strategy may provide a better account than alternative hypotheses. we also further our discussion of the influence of stimulation and experience in early life on lateralization, and thereby show that our hypothesis is not deterministic. we also consider some novel data and ideas in support of our main thesis.

Sodium intake, health implications, and the role of population-level strategies

2020 ◽  
Author(s):  
Ghadeer S Aljuraiban ◽  
Arun Pulikkottil Jose ◽  
Priti Gupta ◽  
Krithiga Shridhar ◽  
Dorairaj Prabhakaran
Keyword(s):  
Sodium Intake ◽  
Population Level ◽  
World Health ◽  
Current Evidence ◽  
Health Implications ◽  
High Sodium ◽  
Reduce Sodium Intake ◽  
Matters Of Concern

Abstract Evidence to date suggests that high sodium intake affects health adversely, yet the role of a population-level strategy to reduce sodium intake is often contested. This review focuses on current available evidence on regional sodium intake levels, health implications of sodium intake, and population-level strategies implemented worldwide. The limitations in evidence, the difficulties in implementing population-wide strategies to reduce sodium intake, and the need for such strategies are critically reviewed. Evidence clearly shows that sodium has an adverse effect on blood pressure, cardiovascular disease, and mortality. However, whether reduced sodium intake benefits all individuals or only hypertensive individuals is still unclear. Methodological issues and publication bias in current evidence are other matters of concern in sodium-related research. While it is essential to continue working toward the World Health Organization’s target of 30% reduction in sodium intake, due consideration should be given to improving the quality of research, reducing bias in publications, and reviewing evidence more critically.

Effectiveness of various methods of home fortification in under-5 children: where they work, where they do not. A systematic review and meta-analysis

2020 ◽  
Author(s):  
Bahareh Nikooyeh ◽  
Tirang R Neyestani
Keyword(s):  
Systematic Review ◽  
Vitamin A ◽  
Serum Zinc ◽  
Population Level ◽  
Child Growth ◽  
Current Evidence ◽  
Cochrane Library ◽  
Micronutrient Deficiencies ◽  
The Impact ◽  
Home Fortification

Abstract Context The common approaches of home fortification (HF) for prevention and/or treatment of micronutrient deficiencies are micronutrient powders (MNPs), foodlets, and lipid-based nutrient supplements (LNSs). There are mixed results for the impact of HF on growth and nutritional status of young children. Objective This systematic review was prepared in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to evaluate current evidence from randomized controlled trials including children younger than 5 years to assess the effect of strategies of HF on growth and micronutrient status. Methods The MEDLINE, PubMed, Embase, Cochrane Library, and Google Scholar databases were searched to July 2018. A total of 1301 studies were found in a preliminary search. After screening of titles and abstracts, 30 studies were selected. Results Treatment with MNPs, foodlets, and LNSs effectively increased hemoglobin concentrations by at least 2.52 g/L, 4.59 g/L, and 4.4 g/dL, respectively, as compared with a control. There was a significant decrease in risk of anemia development after foodlet intervention compared with a control or iron drops (odds ratio, 0.27; 95%CI, 0.10–0.74; P = 0.01). However, these interventions did not result in any significant improvement in z-scores for changes of height for age, weight for age, and weight for height. The results indicated that MNP (7.16; 95%CI, 0.31–14.01; P = 0.04) and foodlet treatment (4.92; 95%CI, 0.28–9.57; P = 0.04) could increase serum zinc levels. However, none of the home fortification methods improved vitamin A status in the target group. Conclusion Home fortification can be used as an effective method to improve hemoglobin, iron, and zinc status, although in this study it had no effect on vitamin A or anthropometric indicators of the target population. More investigations are warranted for newer approaches of HF to improve a broader range of micronutrients as well as child growth indices and for evaluation of the coverage, compliance, and consistency of such interventions at the population level. PROSPERO Registration No.: CRD42018109279

scholarly journals Ecological traps: current evidence and future directions

2016 ◽  
Vol 283 (1824) ◽  
pp. 20152647 ◽  
Author(s):  
Robin Hale ◽  
Stephen E. Swearer
Keyword(s):  
Population Level ◽  
Current Evidence ◽  
Future Research ◽  
Population Declines ◽  
Future Directions ◽  
Taxonomic Distribution ◽  
Behavioural Effects ◽  
Improved Methods ◽  
Rapid Environmental Change ◽  
Conservation And Management

Ecological traps, which occur when animals mistakenly prefer habitats where their fitness is lower than in other available habitats following rapid environmental change, have important conservation and management implications. Empirical research has focused largely on assessing the behavioural effects of traps, by studying a small number of geographically close habitat patches. Traps, however, have also been defined in terms of their population-level effects (i.e. as preferred habitats of sufficiently low quality to cause population declines), and this is the scale most relevant for management. We systematically review the ecological traps literature to (i) describe the geographical and taxonomic distribution of efforts to study traps, (ii) examine how different traps vary in the strength of their effects on preference and fitness, (iii) evaluate the robustness of methods being used to identify traps, and (iv) determine whether the information required to assess the population-level consequences of traps has been considered. We use our results to discuss key knowledge gaps, propose improved methods to study traps, and highlight fruitful avenues for future research.

scholarly journals Examining the Evidence on the Impact of Nutrition Policies on Child Health and Undernutrition Globally: A Scoping Review (P22-017-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Nandita Perumal ◽  
Beverly Bradley ◽  
Aviva Rappaport ◽  
Vanessa Pike ◽  
Stanley Zlotkin
Keyword(s):  
Child Health ◽  
Scoping Review ◽  
Population Level ◽  
Child Growth ◽  
High Income ◽  
Primary Data ◽  
Current Evidence ◽  
Food Fortification ◽  
Nutrition Policies ◽  
The Impact

Abstract Objectives To summarize the evidence on the impact of nutrition policies on improving health among children in low-, middle- and high-income countries (LMHICs). Methods A scoping review was conducted to map and describe peer-reviewed studies evaluating the impact of population-level nutrition policies on child health and undernutrition (using primary data) in LMHICs. We systematically searched Medline, Embase, Web of Science, Scopus, and PAIS Index for public policy, to identify eligible studies. Data on key study characteristics, including research design, type of nutrition policy, time span of policy, child's age at outcome assessment, and types of outcomes assessed, were abstracted. Abstract screening and data abstraction were conducted in duplicate and reconciled. Results Of the 5646 abstracts screened, 83 studies were included. The majority of studies were conducted in upper-middle or high-income settings (66%, 54/83 studies) (Figure 1). Most studies were observational study design (49%, 41/83 studies), evaluated regional/sub-national policies (68%, 56/83 studies), reported on mandatory policies (71%, 59/83 studies), were related to micronutrient food fortification and/or supplementation (70%, 58/83 studies), and assessed outcomes among children <5 years of age (55%, 46/83 studies). Iodine deficiency disorders (40%, 33 studies) and neural tube defects (18%, 15 studies) were the most commonly assessed child health outcomes. The impact of policy intervention on outcomes, such as low birth weight, breastfeeding rates, vitamin A deficiencies, and child growth, were assessed less frequently. Policies were largely implemented between 1990–2000 (36%, 30/83 studies) and studies mostly evaluated effects within a year (28%, 23/83) or within 2–5 years since policy implementation (13%, 11/83 studies). Conclusions Among the studies reviewed, nutrition policies were commonly associated with improved child nutrition and health. However, current evidence is primarily based on regional studies from high-income settings evaluating the effect of micronutrient food fortification and/or supplementation policies on a narrow set of outcomes. Further research is needed to assess the impact of a broader range of nutrition policies on child health, particularly in LMICs. Funding Sources Funding for this research was provided by the 2017 SickKids Centre for Global Child Health Catalyst Grant Competition. Supporting Tables, Images and/or Graphs

Sign in / Sign up

Export Citation Format

Share Document