scholarly journals An International Cross-cohort Harmonization and Data Integration Initiative towards Achieving Statistical Power and Meaningful Results

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Tanya Flanagan ◽  
Isabel Fortier ◽  
Mélanie Fon Sing ◽  
Celine Moore
Keyword(s):  
Health Outcomes ◽  
Cohort Studies ◽  
Statistical Power ◽  
Large Scale ◽  
Analytical Approach ◽  
Research Question ◽  
Retrospective Data ◽  
Proof Of Concept ◽  
Factors Affecting ◽  
Data Harmonization

ABSTRACT ObjectivesThe complex interaction between lifestyle, behaviours, genetic factors and the social and physical environment have a fundamental role in modulating risk and/ or progression of health outcomes, especially cancer. To address this complexity, access to large-scale cohorts involving hundreds of thousands of participants and collecting comprehensive and valuable information are required. In the real world however, attaining adequate statistical power presents a major challenge. Retrospective data harmonization and integration across multiple cohort studies has been shown to be an effective analytical approach to attaining statistical power, with the potential to support population health research and policy related questions and improve our understanding of the complex factors affecting health outcomes. ApproachLarge cohorts, with at least 50,000 participants, initiated in countries all over the world, focused on innovative research on cancer and other chronic diseases were invited to participate in this retrospective data harmonization initiative. Cohorts shared their comprehensive metadata related to their study content and design. Almost 150 variables, selected for their relevance to be part of a generic set of information useful for a broad range of research question, were assessed for their harmonization potential and made available on an online searchable study catalogue. Lastly, a proof of concept research question on the retrospective harmonized data was conducted and aimed to investigate methods to analyze individual patient data from multiple studies by studying the determinants associated with age at menopause. ResultsEight cohorts from multiple countries shared their comprehensive metadata related to their study content and design, resulting in over 2 million study participants. Of the 150 potential variables, the majority of them were harmonizable for co-analysis. The proof of concept research question, applied to these variables generated interesting results, widely supported by other research on this topic, found in the literature. This work demonstrates the value of retrospective data harmonization and integration to be an effective analytical approach to attaining statistical power. The searchable study catalogue, available online for researchers to use in their own international research projects offers a new innovative tool for potential co-analysis of similar measures collected by separate cohort studies. ConclusionRetrospective harmonization offers an innovative approach to optimize use of existing research data with increased statistical power.

scholarly journals Data Harmonization and Data Pooling from Cohort Studies: A Practical Approach for Data Management

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Kamala Adhikari ◽  
Scott B Patten ◽  
Alka B Patel ◽  
Shahirose Premji ◽  
Suzanne Tough ◽  
...  
Keyword(s):  
Cohort Studies ◽  
Statistical Power ◽  
Research Question ◽  
Measurement Scale ◽  
Efficient Manner ◽  
Data Pooling ◽  
Response Options ◽  
Data Harmonization ◽  
Cost Efficient ◽  
Single Data

Data pooling from pre-existing multiple datasets can be useful to increase study sample size and statistical power to answer a research question. However, individual datasets may contain variables that measure the same construct differently, posing challenges for data pooling. Variable harmonization, an approach that can generate comparable datasets from heterogeneous sources, can address this issue in some circumstances. As an illustrative example, this paper describes the data harmonization strategies that helped generate comparable datasets across two Canadian pregnancy cohort studies– the All Our Families and the Alberta Pregnancy Outcomes and Nutrition. Variables were harmonized considering multiple features across the datasets: the construct measured; question asked/response options; the measurement scale used; the frequency of measurement; timing of measurement, and the data structure. Completely matching, partially matching, and completely un-matching variables across the datasets were determined based on these features. Variables that were an exact match were pooled as is. Partially matching variables were synchronized across the datasets considering the frequency of measurement, the timing of measurement, and response options. Variables that were completely unmatching could not be harmonized into a single variable. The variable harmonization strategies that were used to generate comparable cohort datasets for data pooling are applicable to other data sources. Future studies may employ or evaluate these strategies. Variable harmonization and pooling provide an opportunity to increase study power and the utility of existing data, permitting researchers to answer novel research questions in a statistically efficient, timely, and cost-efficient manner that could not be achieved using a single data source.

scholarly journals Confound modelling in UK Biobank brain imaging

2020 ◽  
Author(s):  
Fidel Alfaro-Almagro ◽  
Paul McCarthy ◽  
Soroosh Afyouni ◽  
Jesper L. R. Andersson ◽  
Matteo Bastiani ◽  
...  
Keyword(s):  
Health Outcomes ◽  
Cohort Studies ◽  
Brain Imaging ◽  
Statistical Power ◽  
Uk Biobank ◽  
Future Studies ◽  
Essential Step ◽  
Linear Effects ◽  
Unexplained Variance ◽  
High Statistical Power

AbstractDealing with confounds is an essential step in large cohort studies to address problems such as unexplained variance and spurious correlations. UK Biobank is a powerful resource for studying associations between imaging and nonimaging measures such as lifestyle factors and health outcomes, in part because of the large subject numbers. However, the resulting high statistical power also raises the sensitivity to confound effects, which therefore have to be carefully considered. In this work we describe a set of possible confounds (including non-linear effects and interactions) that researchers may wish to consider for their studies using such data. We include descriptions of how we can estimate the confounds, and study the extent to which each of these confounds affects the data, and the spurious correlations that may arise if they are not controlled. Finally, we discuss several issues that future studies should consider when dealing with confounds.

scholarly journals Measuring sleep regularity: Theoretical properties and practical usage of existing metrics

SLEEP ◽  
2021 ◽  
Author(s):  
Dorothee Fischer ◽  
Elizabeth B Klerman ◽  
Andrew J K Phillips
Keyword(s):  
Large Scale ◽  
Research Question ◽  
Group Differences ◽  
Regularity Index ◽  
Wake Patterns ◽  
Health Related ◽  
Phase Deviation ◽  
Unbiased Estimates ◽  
Large Scale Simulations ◽  
Larger Sample

Abstract Study Objectives Sleep regularity predicts many health-related outcomes. Currently, however, there is no systematic approach to measuring sleep regularity. Traditionally, metrics have assessed deviations in sleep patterns from an individual’s average. Traditional metrics include intra-individual standard deviation (StDev), Interdaily Stability (IS), and Social Jet Lag (SJL). Two metrics were recently proposed that instead measure variability between consecutive days: Composite Phase Deviation (CPD) and Sleep Regularity Index (SRI). Using large-scale simulations, we investigated the theoretical properties of these five metrics. Methods Multiple sleep-wake patterns were systematically simulated, including variability in daily sleep timing and/or duration. Average estimates and 95% confidence intervals were calculated for six scenarios that affect measurement of sleep regularity: ‘scrambling’ the order of days; daily vs. weekly variation; naps; awakenings; ‘all-nighters’; and length of study. Results SJL measured weekly but not daily changes. Scrambling did not affect StDev or IS, but did affect CPD and SRI; these metrics, therefore, measure sleep regularity on multi-day and day-to-day timescales, respectively. StDev and CPD did not capture sleep fragmentation. IS and SRI behaved similarly in response to naps and awakenings but differed markedly for all-nighters. StDev and IS required over a week of sleep-wake data for unbiased estimates, whereas CPD and SRI required larger sample sizes to detect group differences. Conclusions Deciding which sleep regularity metric is most appropriate for a given study depends on a combination of the type of data gathered, the study length and sample size, and which aspects of sleep regularity are most pertinent to the research question.

scholarly journals On the geophysical processes impacting palaeo-sea-level observations

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yusuke Yokoyama ◽  
Anthony Purcell
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Global Climate ◽  
Sea Level Change ◽  
Sea Level Changes ◽  
Factors Affecting ◽  
Ice Volume ◽  
Level Change ◽  
Recent Developments ◽  
Geophysical Processes

AbstractPast sea-level change represents the large-scale state of global climate, reflecting the waxing and waning of global ice sheets and the corresponding effect on ocean volume. Recent developments in sampling and analytical methods enable us to more precisely reconstruct past sea-level changes using geological indicators dated by radiometric methods. However, ice-volume changes alone cannot wholly account for these observations of local, relative sea-level change because of various geophysical factors including glacio-hydro-isostatic adjustments (GIA). The mechanisms behind GIA cannot be ignored when reconstructing global ice volume, yet they remain poorly understood within the general sea-level community. In this paper, various geophysical factors affecting sea-level observations are discussed and the details and impacts of these processes on estimates of past ice volumes are introduced.

scholarly journals Progress in Research on Carbon Nanotubes Reinforced Cementitious Composites

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Qinghua Li ◽  
Jintao Liu ◽  
Shilang Xu
Keyword(s):  
Carbon Nanotubes ◽  
Large Scale ◽  
High Strength ◽  
Cementitious Composites ◽  
Scale Production ◽  
Multiwalled Carbon ◽  
Factors Affecting ◽  
Environment And Health ◽  
Research Activities ◽  
Major Factors

As one-dimensional (1D) nanofiber, carbon nanotubes (CNTs) have been widely used to improve the performance of nanocomposites due to their high strength, small dimensions, and remarkable physical properties. Progress in the field of CNTs presents a potential opportunity to enhance cementitious composites at the nanoscale. In this review, current research activities and key advances on multiwalled carbon nanotubes (MWCNTs) reinforced cementitious composites are summarized, including the effect of MWCNTs on modulus of elasticity, porosity, fracture, and mechanical and microstructure properties of cement-based composites. The issues about the improvement mechanisms, MWCNTs dispersion methods, and the major factors affecting the mechanical properties of composites are discussed. In addition, large-scale production methods of MWCNTs and the effects of CNTs on environment and health are also summarized.

Species Responses to Grazing and Environmental-Factors in an Arid Halophytic Shrubland Community

1987 ◽  
Vol 35 (2) ◽  
pp. 135 ◽  
Author(s):  
RB Hacker
Keyword(s):  
Environmental Factors ◽  
Soil Salinity ◽  
Large Scale ◽  
Chemical Properties ◽  
Grazing Pressure ◽  
Aerial Photographs ◽  
Small Scale ◽  
Factors Affecting ◽  
Species Responses

Species responses to grazing and environmental factors were studied in an arid halophytic shrubland community in Western Australia. The grazing responses of major shrub species were defined by using reciprocal averaging ordination of botanical data, interpreted in conjunction with a similar ordination of soil chemical properties and measures of soil erosion derived from large-scale aerial photographs. An apparent small-scale interaction between grazing and soil salinity was also defined. Long-term grazing pressure is apparently reduced on localised areas of high salinity. Environmental factors affecting species distribution are complex and appear to include soil salinity, soil cationic balance, geomorphological variation and the influence of cryptogamic crusts on seedling establishment.

scholarly journals Body Mass Index and Mortality From All Causes and Major Causes in Japanese: Results of a Pooled Analysis of 7 Large-Scale Cohort Studies

2011 ◽  
Vol 21 (6) ◽  
pp. 417-430 ◽  
Author(s):  
Shizuka Sasazuki ◽  
Manami Inoue ◽  
Ichiro Tsuji ◽  
Yumi Sugawara ◽  
Akiko Tamakoshi ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Cohort Studies ◽  
Body Mass ◽  
Large Scale ◽  
Pooled Analysis

Factors affecting post-fire seedling establishment of selected mallee understorey species

2000 ◽  
Vol 48 (1) ◽  
pp. 59 ◽  
Author(s):  
J. S. Cohn ◽  
R. A. Bradstock
Keyword(s):  
Large Scale ◽  
Prescribed Burning ◽  
New South ◽  
Eucalyptus Species ◽  
Factors Affecting ◽  
Acacia Species ◽  
Introduced Herbivores ◽  
South Wales ◽  
Rabbit Grazing ◽  
Seedling Germination

Factors affecting the survival of post-fire germinants in mallee communities, in central western New South Wales, were examined. Experiments compared the relative effects of native and introduced herbivores (kangaroos, goats, rabbits), after small- and large-scale fires (20–50 and > 10 000 ha, respectively), with particular emphasis on edge effects, seedling clustering, topography and eucalypt canopy presence. The experiments (1985–1997) focused on common understorey species Acacia rigens Cunn. ex Don, A. wilhelmiana F.Muell. and Triodia scariosa N.T.Burb. subsp. scariosa, in mallee dominated by Eucalyptus species. Following a large fire (1985), high spring rainfall and rabbit grazing on A. rigens only, survival of Acacia species and T. scariosa remained relatively high 4 years later (60–70%). After small burns (1987, 1988), low spring rainfall and grazing by rabbits and kangaroos, survival of Acacia species declined to between 0 and 30% of the germinants by the second summer. In most cases, local extinction had occurred within 8 years. After small burns (1988, 1989) and low spring rainfall, the survival of T. scariosa declined to between 0 and 35% of germinants by the second summer (effect of grazing unknown). No consistent effect of edge, topography and eucalypt canopy was found. Survival of clustered Acacia seedlings was between 10 and 20% lower than unclustered seedlings. Given the high frequency of low rainfall and its interaction with grazing, prescribed burning of mallee for wildfire control and nature conservation may require the local elimination of rabbits and a reduction in kangaroo numbers, especially in the first spring and summer following seedling germination.

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