scholarly journals A study of variance estimation methods for systematic spatial sampling

2017 ◽  
Vol 21 ◽  
pp. 226-240 ◽  
Author(s):  
Geir-Harald Strand
Keyword(s):  
Variance Estimation ◽  
Spatial Sampling ◽  
Estimation Methods

scholarly journals Meta-Analysis with Robust Variance Estimation: Expanding the Range of Working Models

2020 ◽  
Author(s):  
James E Pustejovsky ◽  
Elizabeth Tipton
Keyword(s):  
Variance Estimation ◽  
Meta Analysis ◽  
Estimation Methods ◽  
Single Type ◽  
Dependence Structure ◽  
Dependent Effect ◽  
Working Models ◽  
Robust Variance ◽  
Robust Variance Estimation ◽  
Meta Regression

In prevention science and related fields, large meta-analyses are common, and these analyses often involve dependent effect size estimates. Robust variance estimation (RVE) methods provide a way to include all dependent effect sizes in a single meta-regression model, even when the nature of the dependence is unknown. RVE uses a working model of the dependence structure, but the two currently available working models are limited to each describing a single type of dependence. Drawing on flexible tools from multivariate meta-analysis, this paper describes an expanded range of working models, along with accompanying estimation methods, which offer benefits in terms of better capturing the types of data structures that occur in practice and improving the efficiency of meta-regression estimates. We describe how the methods can be implemented using existing software (the ‘metafor’ and ‘clubSandwich’ packages for R) and illustrate the approach in a meta-analysis of randomized trials examining the effects of brief alcohol interventions for adolescents and young adults.

scholarly journals Accurate Solution of Navigation Equations in GPS Receivers for Very High Velocities Using Pseudorange Measurements

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
N. Rahemi ◽  
M. R. Mosavi ◽  
A. A. Abedi ◽  
S. Mirzakuchaki
Keyword(s):  
Least Squares ◽  
Navigation System ◽  
Variance Estimation ◽  
Least Squares Method ◽  
Accurate Solution ◽  
Estimation Methods ◽  
Gps Receivers ◽  
The Earth ◽  
Exact Position ◽  
Very High

GPS is a satellite-based navigation system that is able to determine the exact position of objects on the Earth, sky, or space. By increasing the velocity of a moving object, the accuracy of positioning decreases; meanwhile, the calculation of the exact position in the movement by high velocities like airplane movement or very high velocities like satellite movement is so important. In this paper, seven methods for solving navigation equations in very high velocities using least squares method and its combination with the variance estimation methods for weighting observations based on their qualities are studied. Simulations on different data with different velocities from 100 m/s to 7000 m/s show that proposed method can improve the accuracy of positioning more than 50%.

scholarly journals Empirical Study of Travel Time Estimation and Reliability

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Ruimin Li ◽  
Huajun Chai ◽  
Jin Tang
Keyword(s):  
Travel Time ◽  
Time Distribution ◽  
Large Scale ◽  
Variance Estimation ◽  
Time Estimation ◽  
Estimation Methods ◽  
Travel Time Estimation ◽  
Time Variance ◽  
Travel Time Distribution ◽  
Average Travel Time

This paper explores the travel time distribution of different types of urban roads, the link and path average travel time, and variance estimation methods by analyzing the large-scale travel time dataset detected from automatic number plate readers installed throughout Beijing. The results show that the best-fitting travel time distribution for different road links in 15 min time intervals differs for different traffic congestion levels. The average travel time for all links on all days can be estimated with acceptable precision by using normal distribution. However, this distribution is not suitable to estimate travel time variance under some types of traffic conditions. Path travel time can be estimated with high precision by summing the travel time of the links that constitute the path. In addition, the path travel time variance can be estimated by the travel time variance of the links, provided that the travel times on all the links along a given path are generated by statistically independent distributions. These findings can be used to develop and validate microscopic simulations or online travel time estimation and prediction systems.

EFFECTS OF SAMPLING VARIANCE ESTIMATION METHODS ON PRECISION OF SMALL AREA ESTIMATION

2017 ◽  
Vol 14 (2) ◽  
pp. 93-106
Author(s):  
Mojtaba Soltani-Kermanshahi ◽  
Yadollah Mehrabi ◽  
Amir Kavousi ◽  
Ahmad-Reza Baghestani ◽  
Fatemeh Mohammadi-Nasrabadi
Keyword(s):  
Small Area ◽  
Variance Estimation ◽  
Small Area Estimation ◽  
Estimation Methods ◽  
Sampling Variance ◽  
Area Estimation
Sign in / Sign up

Export Citation Format

Share Document