A Critique of the Practice of Comparing Control Data Obtained At A Single Time Point to Experimental Data Obtained At Multiple Time Points

ObjectiveCardiovascular disease (CVD) incidence is elevated among people with psychological distress. However, whether the relationship is causal is unclear, partly due to methodological limitations, including limited evidence relating to longer-term rather than single time-point measures of distress. We compared CVD relative risks for psychological distress using single time-point and multi-time-point assessments using data from a large-scale cohort study.DesignWe used questionnaire data, with data collection at two time-points (time 1: between 2006 and 2009; time 2: between 2010 and 2015), from CVD-free and cancer-free 45 and Up Study participants, linked to hospitalisation and death records. The follow-up period began at time 2 and ended on 30 November 2017. Psychological distress was measured at both time-points using Kessler 10 (K10), allowing assessment of single time-point (at time 2: high (K10 score: 22–50) vs low (K10 score: <12)) and multi-time-point (high distress (K10 score: 22–50) at both time-points vs low distress (K10 score: <12) at both time-points) measures of distress. Cox regression quantified the association between distress and major CVD, with and without adjustment for sociodemographic and health-related characteristics, including functional limitations.ResultsAmong 83 906 respondents, 7350 CVD events occurred over 410 719 follow-up person-years (rate: 17.9 per 1000 person-years). Age-adjusted and sex-adjusted rates of major CVD were elevated by 50%–60% among those with high versus low distress for both the multi-time-point (HR=1.63, 95% CI 1.40 to 1.90) and single time-point (HR=1.53, 95% CI 1.39 to 1.69) assessments. HRs for both measures of distress attenuated with adjustment for sociodemographic and health-related characteristics, and there was little evidence of an association when functional limitations were taken into account (multi-time-point HR=1.09, 95% CI 0.93 to 1.27; single time-point HR=1.14, 95% CI 1.02 to 1.26).ConclusionIrrespective of whether a single time-point or multi-time-point measure is used, the distress–CVD relationship is substantively explained by sociodemographic characteristics and pre-existing physical health-related factors.

Download Full-text

Faculty Opinions recommendation of Molecular-timetable methods for detection of body time and rhythm disorders from single-time-point genome-wide expression profiles.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1021199.242550 ◽

2004 ◽

Author(s):

Victor Reus

Keyword(s):

Expression Profiles ◽

Single Time ◽

Genome Wide ◽

Genome Wide Expression ◽

Single Time Point ◽

Time Point

Download Full-text

Use of TanDEM-X and SRTM-C Data for Detection of Deforestation Caused by Bark Beetle in Central European Mountains

Remote Sensing ◽

10.3390/rs13153042 ◽

2021 ◽

Vol 13 (15) ◽

pp. 3042

Author(s):

Kateřina Gdulová ◽

Jana Marešová ◽

Vojtěch Barták ◽

Marta Szostak ◽

Jaroslav Červenka ◽

...

Keyword(s):

Bark Beetle ◽

Synergistic Effects ◽

Canopy Height ◽

Surface Model ◽

Multiple Time ◽

Central European ◽

Time Points ◽

Bohemian Forest ◽

Multiple Time Points ◽

Surrounding Areas

The availability of global digital elevation models (DEMs) from multiple time points allows their combination for analysing vegetation changes. The combination of models (e.g., SRTM and TanDEM-X) can contain errors, which can, due to their synergistic effects, yield incorrect results. We used a high-resolution LiDAR-derived digital surface model (DSM) to evaluate the accuracy of canopy height estimates of the aforementioned global DEMs. In addition, we subtracted SRTM and TanDEM-X data at 90 and 30 m resolutions, respectively, to detect deforestation caused by bark beetle disturbance and evaluated the associations of their difference with terrain characteristics. The study areas covered three Central European mountain ranges and their surrounding areas: Bohemian Forest, Erzgebirge, and Giant Mountains. We found that vertical bias of SRTM and TanDEM-X, relative to the canopy height, is similar with negative values of up to −2.5 m and LE90s below 7.8 m in non-forest areas. In forests, the vertical bias of SRTM and TanDEM-X ranged from −0.5 to 4.1 m and LE90s from 7.2 to 11.0 m, respectively. The height differences between SRTM and TanDEM-X show moderate dependence on the slope and its orientation. LE90s for TDX-SRTM differences tended to be smaller for east-facing than for west-facing slopes, and varied, with aspect, by up to 1.5 m in non-forest areas and 3 m in forests, respectively. Finally, subtracting SRTM and NASA DEMs from TanDEM-X and Copernicus DEMs, respectively, successfully identified large areas of deforestation caused by hurricane Kyril in 2007 and a subsequent bark beetle disturbance in the Bohemian Forest. However, local errors in TanDEM-X, associated mainly with forest-covered west-facing slopes, resulted in erroneous identification of deforestation. Therefore, caution is needed when combining SRTM and TanDEM-X data in multitemporal studies in a mountain environment. Still, we can conclude that SRTM and TanDEM-X data represent suitable near global sources for the identification of deforestation in the period between the time points of their acquisition.

Download Full-text

Meta-analysis of effect sizes reported at multiple time points: A multivariate approach

Clinical Trials ◽

10.1177/1740774512453218 ◽

2012 ◽

Vol 9 (5) ◽

pp. 610-620 ◽

Cited By ~ 28

Author(s):

Thomas A Trikalinos ◽

Ingram Olkin

Keyword(s):

Random Effects ◽

Treatment Effects ◽

Multivariate Analyses ◽

Meta Analysis ◽

Effect Sizes ◽

Multiple Time ◽

Time Points ◽

Fixed And Random Effects ◽

Multiple Time Points ◽

Meta Analyses

Background Many comparative studies report results at multiple time points. Such data are correlated because they pertain to the same patients, but are typically meta-analyzed as separate quantitative syntheses at each time point, ignoring the correlations between time points. Purpose To develop a meta-analytic approach that estimates treatment effects at successive time points and takes account of the stochastic dependencies of those effects. Methods We present both fixed and random effects methods for multivariate meta-analysis of effect sizes reported at multiple time points. We provide formulas for calculating the covariance (and correlations) of the effect sizes at successive time points for four common metrics (log odds ratio, log risk ratio, risk difference, and arcsine difference) based on data reported in the primary studies. We work through an example of a meta-analysis of 17 randomized trials of radiotherapy and chemotherapy versus radiotherapy alone for the postoperative treatment of patients with malignant gliomas, where in each trial survival is assessed at 6, 12, 18, and 24 months post randomization. We also provide software code for the main analyses described in the article. Results We discuss the estimation of fixed and random effects models and explore five options for the structure of the covariance matrix of the random effects. In the example, we compare separate (univariate) meta-analyses at each of the four time points with joint analyses across all four time points using the proposed methods. Although results of univariate and multivariate analyses are generally similar in the example, there are small differences in the magnitude of the effect sizes and the corresponding standard errors. We also discuss conditional multivariate analyses where one compares treatment effects at later time points given observed data at earlier time points. Limitations Simulation and empirical studies are needed to clarify the gains of multivariate analyses compared with separate meta-analyses under a variety of conditions. Conclusions Data reported at multiple time points are multivariate in nature and are efficiently analyzed using multivariate methods. The latter are an attractive alternative or complement to performing separate meta-analyses.

Download Full-text

Single Time Point Interventions in Network-Dependent Data

Springer Series in Statistics - Targeted Learning in Data Science ◽

10.1007/978-3-319-65304-4_21 ◽

2018 ◽

pp. 373-396

Author(s):

Oleg Sofrygin ◽

Elizabeth L. Ogburn ◽

Mark J. van der Laan

Keyword(s):

Dependent Data ◽

Single Time ◽

Single Time Point ◽

Time Point

Download Full-text

Bidirectional saturable transport of LHRH across the blood-brain barrier

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1991.261.3.e312 ◽

1991 ◽

Vol 261 (3) ◽

pp. E312-E318 ◽

Cited By ~ 4

Author(s):

C. M. Barrera ◽

A. J. Kastin ◽

M. B. Fasold ◽

W. A. Banks

Keyword(s):

Blood Brain Barrier ◽

Ovarian Function ◽

Brain Barrier ◽

Multiple Time ◽

Blood Brain ◽

Permeability Surface ◽

Cerebrovascular Permeability ◽

The Difference ◽

Single Time Point ◽

Time Point

Systemic administration of luteinizing hormone-releasing hormone (LHRH) in rats has been found to influence behavior independently of pituitary or ovarian function. A previous study has shown that LHRH can cross the blood-brain barrier in one direction, but it was not known whether this was due to a saturable transport system. The rate of entry of 125I-labeled LHRH from blood to brain was determined by two different single-pass methods of carotid perfusion. The first, a multiple time point method, measures Ki from the slope of the linear regression when brain-to-blood ratios of radioiodinated LHRH are plotted against time. Saturable transport was determined by the difference between the Ki of rats perfused with 125I-LHRH (12.51 X 10(-3) mg.g-1.min-1) vs. rats perfused with 125I-LHRH and unlabeled LHRH (10 nmol/ml; 2.20 X 10(-3) ml.g-1.min-1). The inhibition by the unlabeled peptide was statistically significant (P less than 0.001). The second method, a single time point technique, measures the cerebrovascular permeability-surface area coefficient (PA). Saturable transport was determined in rats by the competition of unlabeled LHRH with 125I-LHRH. The PA value for 125I-LHRH (20.00 X 10(-3) ml.g-1.min-1) was significantly greater (P less than 0.05) than for 125I-LHRH with the addition of 10 nmol/ml unlabeled LHRH (4.14 X 10(-3) ml.g-1.min-1). Saturable transport of LHRH from brain to blood in mice was also determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

THE ROLE OF MEMORY PERSPECTIVE IN SOCIAL PHOBIA: IMMEDIATE AND DELAYED MEMORIES FOR ROLE-PLAYED SITUATIONS

Behavioural and Cognitive Psychotherapy ◽

10.1017/s1352465802004034 ◽

2002 ◽

Vol 30 (4) ◽

pp. 415-425 ◽

Cited By ~ 34

Author(s):

Meredith E. Coles ◽

Cynthia L. Turk ◽

Richard G. Heimberg

Keyword(s):

Social Phobia ◽

Multiple Time ◽

Behavioral Models ◽

Social Situations ◽

Time Points ◽

Cognitive Behavioral Models ◽

Multiple Time Points ◽

Memory Perspective ◽

Field Perspective

Cognitive-behavioral models (Clark & Wells, 1995; Rapee & Heimberg, 1997) and recent research suggest that individuals with social phobia (SP) experience both images (Hackmann, Surawy, & Clark, 1998) and memories (Coles, Turk, Heimberg, & Fresco, 2001; Wells, Clark, & Ahmad, 1998) of anxiety-producing social situations from an observer perspective. The current study examines memory perspective for two role-played situations (speech and social interaction) at multiple time points (immediate and 3 weeks post) in 22 individuals with generalized SP and 30 non-anxious controls (NACs). At both time points, SPs recalled the role-plays from a more observer/less field perspective than did NACs. Further, over time, the memory perspective of SPs became even more observer/less field while the memory perspective of NAC remained relatively stable.

Download Full-text

A combination of different diagnostic tools allows identification of inactive hepatitis B virus carriers at a single time point evaluation

Liver International ◽

10.1111/liv.13246 ◽

2016 ◽

Vol 37 (3) ◽

pp. 362-368 ◽

Cited By ~ 8

Author(s):

Sergio Maimone ◽

Gaia Caccamo ◽

Giovanni Squadrito ◽

Angela Alibrandi ◽

Francesca Saffioti ◽

...

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Diagnostic Tools ◽

Point Evaluation ◽

Single Time ◽

B Virus ◽

Single Time Point ◽

Time Point

Download Full-text

The Silicon Peaches

Innovation in Real Places ◽

10.1093/oso/9780197508114.003.0003 ◽

2021 ◽

pp. 31-42

Author(s):

Dan Breznitz

Keyword(s):

Information And Communication Technologies ◽

Silicon Valley ◽

Communication Technologies ◽

Multiple Time ◽

Rapid Rise ◽

Time Points ◽

Start Up ◽

Information And Communication ◽

Multiple Time Points ◽

Start Ups

This chapter acknowledges that, for many regions, the idea of attracting cutting-edge tech start-ups is almost irresistible. Seemingly every community aspires to become the next Silicon Valley. But is that feasible? This chapter make these lessons concrete by elaborating on the rapid rise and, even faster and deeper, decline of America’s first Silicon Valley—Cleveland, Ohio. It then shows the near impossibility of trying to become the next Silicon Valley by analyzing the mysterious failure of Atlanta, Georgia—a city that diligently followed all the advice ever given to an aspiring new start-up hub, but somehow was always left only with the “potential.” We will see how at multiple time-points Atlanta’s companies were the leading innovators with the best products in the newest information and communication technologies (ICT), only to falter and be taken over by Silicon Valley companies without leaving any apparent impact on the region. It then brings in social-network research and the concept of embeddedness to explain why trying to recreate a Silicon Valley is a doomed (and expensive) enterprise.

Download Full-text