Search results for "variance"
showing 10 items of 2030 documents
Consistency tendency and the theory of planned behavior : a randomized controlled crossover trial in a physical activity context
2020
Objective: This study examined the effects of consistency tendency on the predictive power of the theory of planned behavior (TPB) in relation to physical activity behavior. Methods: In this randomized controlled cross-over trial, we recruited 770 undergraduate students from Indonesia who were randomly assigned into two groups. Participants completed physical activity versions of TPB measures at T1 (baseline) and T2 (post 1 week), and the International Physical Activity Questionnaire at T3 (post 1 month). At T1 and T2, the TPB questions were either presented in ensemble-order (i.e., consistency tendency supressed) or alternate-order (i.e., consistency tendency facilitated). Results: The par…
Statistical upscaling of ecosystem CO2 fluxes across the terrestrial tundra and boreal domain: Regional patterns and uncertainties
2021
The regional variability in tundra and boreal carbon dioxide (CO2) fluxes can be high, complicating efforts to quantify sink-source patterns across the entire region. Statistical models are increasingly used to predict (i.e., upscale) CO2 fluxes across large spatial domains, but the reliability of different modeling techniques, each with different specifications and assumptions, has not been assessed in detail. Here, we compile eddy covariance and chamber measurements of annual and growing season CO2 fluxes of gross primary productivity (GPP), ecosystem respiration (ER), and net ecosystem exchange (NEE) during 1990–2015 from 148 terrestrial high-latitude (i.e., tundra and boreal) sites to a…
Applicability and consequences of the integration of alternative models for CO2 transfer velocity into a process-based lake model
2019
Freshwater lakes are important in carbon cycling, especially in the boreal zone where many lakes are supersaturated with the greenhouse gas carbon dioxide (CO2) and emit it to the atmosphere, thus ventilating carbon originally fixed by the terrestrial system. The exchange of CO2 between water and the atmosphere is commonly estimated using simple wind-based parameterizations or models of gas transfer velocity (k). More complex surface renewal models, however, have been shown to yield more correct estimates of k in comparison with direct CO2 flux measurements. We incorporated four gas exchange models with different complexity into a vertical process-based physico-biochemical lake model, MyLak…
The ABCflux database: Arctic-boreal CO2flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems
2022
Past efforts to synthesize and quantify the magnitude and change in carbon dioxide (CO2) fluxes in terrestrial ecosystems across the rapidly warming Arctic–boreal zone (ABZ) have provided valuable information but were limited in their geographical and temporal coverage. Furthermore, these efforts have been based on data aggregated over varying time periods, often with only minimal site ancillary data, thus limiting their potential to be used in large-scale carbon budget assessments. To bridge these gaps, we developed a standardized monthly database of Arctic–boreal CO2 fluxes (ABCflux) that aggregates in situ measurements of terrestrial net ecosystem CO2 exchange and its derived partitioned…
Effects of menu structure and touch screen scrolling style on the variability of glance durations during in-vehicle visual search tasks.
2011
The effects of alternative navigation device display features on drivers' visual sampling efficiency while searching forpoints of interest were studied in two driving simulation experiments with 40 participants. Given that the number of display items was sufficient, display features that facilitate resumption of visual search following interruptions were expected to lead to more consistent in-vehicle glance durations. As predicted, compared with a grid-style menu, searching information in a list-style menu while driving led to smaller variance in durations of in-vehicle glances, in particular with nine item displays. Kinetic touch screen scrolling induced a greater number of very short in-v…
Dangerous relationships : biases in freshwater bioassessment based on observed to expected ratios
2018
Copyright by the Ecological Society of America The ecological assessment of freshwaters is currently primarily based on biological communities and the reference condition approach (RCA). In the RCA, the communities in streams and lakes disturbed by humans are compared with communities in reference conditions with no or minimal anthropogenic influence. The currently favored rationale is using selected community metrics for which the expected values (E) for each site are typically estimated from environmental variables using a predictive model based on the reference data. The proportional differences between the observed values (O) and E are then derived, and the decision rules for status ass…
Self-Efficacy Between Previous and Current Mathematics Performance of Undergraduate Students: An Instrumental Variable Approach to Exposing a Causal …
2021
PurposeSelf-efficacy has been argued theoretically and shown empirically to be an essential construct for students’ improved learning outcomes. However, there is a dearth of studies on its causal effects on performance in mathematics among university students. Meanwhile, it will be erroneous to assume that results from other fields of studies generalize to mathematics learning due to the task-specificity of the construct. As such, attempts are made in the present study to provide evidence for a causal relationship between self-efficacy and performance with a focus on engineering students following a mathematics course at a Norwegian university.MethodThe adopted research design in the presen…
Investigating applicability of ratings of indicators of the CLASS Pre-K instrument
2022
When classroom observations are increasingly used for accountability and evaluation purposes, a deeper understanding of the psychometric properties of such measurement tools is needed. The present study took a unique approach to examine the psychometric properties of a commonly used classroom observation measure by testing the reliability of indicators for higher-order constructs (i.e. dimensions). We investigated the reliability of indicator ratings of the Classroom Assessment Scoring System (CLASS) Pre-K instrument in Finnish kindergarten and first grade classrooms. Twenty-one observer pairs rated 838 segments identified from the 413 lessons of 48 teachers. Variance components models were…
Testing effects of Lorentz invariance violation in the propagation of astroparticles with the Pierre Auger Observatory
2021
The successful installation, commissioning, and operation of the Pierre Auger Observatory would not have been possible without the strong commitment and effort from the technical and administrative staff in Malargüe. We are very grateful to the following agencies and organizations for financial support: Argentina — Comisión Nacional de Energía Atómica; Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Gobierno de la Provincia de Mendoza; Municipalidad de Malargüe; NDM Holdings and Valle Las Leñas; in gratitude for their continuing cooperation over land access; Australia — the Australian Research Council; Be…
Prematurity and overlap between reading and arithmetic: The cognitive mechanisms behind the association
2019
It is well-known that very preterm children perform at lower levels than full-term children in reading and arithmetic at school. Whether the lower performance levels of preterm children in these two separate domains have the same or different origins, however, is not clear. The present study examined the extent to which prematurity is associated with the overlap (i.e., common variance) of reading and arithmetic among Finnish school beginners. We also examined the extent to which the association of prematurity with the overlap between reading and arithmetic is due to different prereading skills, basic number skills, and general cognitive abilities. The participants (age 6-7) consisted of 193…