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- Household surveys (3)
- Sample design (2)
- Chemistry (1)
- Cluster sampling (1)
- Cost–variance optimization (1)
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- Design effect (1)
- During (1)
- Environment (1)
- Estimation (1)
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- Generalized regression estimator (1)
- Health surveys (1)
- Household (1)
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- POCl3 (1)
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- Reaction (1)
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- Rotating panel survey (1)
- Sampling subpopulations (1)
- Soil (1)
- Spatial analysis; variograms; bootstrap; jackknife; block bootstrap; block jackknife (1)
- Survey design (1)
- Surveys (1)
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Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
Person-Level And Household-Level Regression Estimation In Household Surveys, David Steel, Robert Clark
Person-Level And Household-Level Regression Estimation In Household Surveys, David Steel, Robert Clark
Robert Clark
A common class of survey designs involves selecting all people within selected households. Generalized regressionestimators can be calculated at either the person or household level. Implementing the estimator at the household level has the convenience of equal estimation weights for people within households. In this article the two approaches are compared theoretically and empirically for the case of simple random sampling of households and selection of all persons in each selected household. We find that the household level approach is theoretically more efficient in large samples and any empirical inefficiency in small samples is limited.
Comments On Sample Design For Proposed Australian Asthma Survey, Robert Clark
Comments On Sample Design For Proposed Australian Asthma Survey, Robert Clark
Robert Clark
The proposed design for the Australian Asthma Survey involves: a phone or face-toface screening interview with approximately 20,000 responding adults, followed by an in-depth interview and objective testing of all asthmatics and 1/10th of nonasthmatics in the screen. This report elaborates on sample design options based on the aims and approaches in the Australian Asthma Survey Proposal. The main requirement affecting the sample design is the need for a relatively small number of objective testing centres to be able to service the whole sample. This report considered a number of options where the sample was clustered in only 25 Statistical …
Oxygen Exchange During The Reaction Of Pocl3 And Water, Robert Clark, Robert Morrison, Andrew Thomas, Rebeca Alvarez, Paul Milham
Oxygen Exchange During The Reaction Of Pocl3 And Water, Robert Clark, Robert Morrison, Andrew Thomas, Rebeca Alvarez, Paul Milham
Robert Clark
To investigate O exchange during the reaction of POCl3 and water, natural abundance POCl3 was reacted with water highly enriched in 18O, and the resulting H3PO4 was isolated as KH2PO4. This reaction was conducted with and without tetrahydrofuran (THF) as a solvent, and was controlled in THF and violent in its absence. Approximately 5 x 10-4M aqueous solutions of the KH2PO4 were analyzed using electrospray ionization mass spectrometry, to estimate the proportions of the mass-clumped 16,17,18O isotope analogues of [H2PO4] -. During analysis, ~29% of [H2PO4] - dehydrated to [PO3]-, for which the proportions of the O isotope analogues were …
Robust Resampling Confidence Intervals For Empirical Variograms, Robert Clark, Samuel Allingham
Robust Resampling Confidence Intervals For Empirical Variograms, Robert Clark, Samuel Allingham
Robert Clark
The variogram function is an important measure of the spatial dependenciesof a geostatistical or other spatial dataset. It plays a central role in kriging, designingspatial studies, and in understanding the spatial properties of geological andenvironmental phenomena. It is therefore important to understand the variability attachedto estimates of the variogram. Existing methods for constructing confidenceintervals around the empirical variogram either rely on strong assumptions, such asnormality or known variogram function, or are based on resampling blocks and subjectto edge effect biases. This paper proposes two new procedures for addressingthese concerns: a quasi-block-bootstrap and a quasi-block-jackknife. The new methodsare based on transforming …
Sampling Within Households In Household Surveys, Robert Clark, David Steel
Sampling Within Households In Household Surveys, Robert Clark, David Steel
Robert Clark
The number of people to select within selected households has significant consequences for the conduct and output of household surveys. The operational and data quality implications of this choice are carefully considered in many surveys, but the impact on statistical efficiency is not well understood. The usual approach is to select all people in each selected household, where operational and data quality concerns make this feasible. If not, one person is usually selected from each selected household. We find that this strategy is not always justified, and develop intermediate designs between these two extremes. Current practices were developed when household …
Preliminary Sample Design For The New Zealand Health Survey 2010, Robert Clark
Preliminary Sample Design For The New Zealand Health Survey 2010, Robert Clark
Robert Clark
This report describes the choice of the preliminary design for the New Zealand Health Survey, to be implemented from 2011. The survey will use computer assisted personal interviewing. The sample will be selected using a multi-stage area design. The selected sample size will be around 12,000 people per year. This is envisaged as sufficient to provide adequate precision for estimates of key prevalences for adults and children. The main objectives of the sample design are: • The design should support analysis of the survey by multiple users, which implies avoiding great variation in estimation weights. • Estimates for children and …
Accounting For The Uncertainty Of Information On Clustering In The Design Of A Clustered Sample, David Steel, Robert Clark
Accounting For The Uncertainty Of Information On Clustering In The Design Of A Clustered Sample, David Steel, Robert Clark
Robert Clark
An important decision that has to be made in developing the design of a cluster or multi-stage sampling scheme is the number of units to select at each stage of selection. For a two-stage design we need to decide the number of units to select from each Primary Sampling Unit (PSU) in the sample. A common approach is to estimate the costs and the variance components associated with each stage of selection and determine an optimal design. This is usually done for estimates of the means or totals of one or a small number of variables. In practice the measure …
The Effect Of Using Household As A Sampling Unit, Robert Clark, David Steel
The Effect Of Using Household As A Sampling Unit, Robert Clark, David Steel
Robert Clark
The effect of sampling people through households is considered. Results on design effects for two stage surveys are reviewed and applied to give design effects of household samples. The main factors that determine the design effect are identified for the designs in which one person, or all people, are selected from each selected household.Within household correlation is one factor.We show that the relationships between household size and the mean and variance within households are also important factors. Census and survey data are used to empirically compare the design effects for a range of estimators, variables and designs.
Conditional And Unconditional Models In Model-Assisted Estimation Of Finite Population Totals, David Steel, Robert Clark
Conditional And Unconditional Models In Model-Assisted Estimation Of Finite Population Totals, David Steel, Robert Clark
Robert Clark
The well known Godambe-Joshi lower bound for the anticipated variance of design unbiased estimators of population totals treats the auxiliary variables as constants. We extend the result to models where these variables are random and show that the generalized difference estimator using the expected values conditional on all auxiliary values is optimal. This has several implications including the fact that collecting multiple survey variables does not reduce the lower bound.
Adaptive Inference For Multi-Stage Survey Data, Loai Alzoubi, Robert Clark, David Steel
Adaptive Inference For Multi-Stage Survey Data, Loai Alzoubi, Robert Clark, David Steel
Robert Clark
Multi-level models can be used to account for clustering in data from multi-stage surveys. In some cases, the intraclass correlation may be close to zero, so that it may seem reasonable to ignore clustering and fit a single-level model. This article proposes several adaptive strategies for allowing for clustering in regression analysis of multi-stage survey data. The approach is based on testing whether the PSU-level variance component is zero. If this hypothesis is retained, then variance estimates are calculated ignoring clustering; otherwise, clustering is reflected in variance estimation. A simple simulation study is used to evaluate the various procedures.
Soil Chemistry: Understanding Phosphorus In The Environment, Paul Milham, Warwick Dougherty, Robert Morrison, Robert Clark, Ronald Smernik, Ashlea Doolette, Lucy Burkitt, Damian Collins, Rebeca Alvarez, Andrew Thomas
Soil Chemistry: Understanding Phosphorus In The Environment, Paul Milham, Warwick Dougherty, Robert Morrison, Robert Clark, Ronald Smernik, Ashlea Doolette, Lucy Burkitt, Damian Collins, Rebeca Alvarez, Andrew Thomas
Robert Clark
It is an essential ingredient in food production, but poor management means bad news downstream. Understanding the way phosphorus behaves in the environment calls for soil and plant biology, and some new soil chemistry.
Design And Analysis Of Clustered, Unmatched Resource Selection Studies, Robert Clark, Tanya Strevens
Design And Analysis Of Clustered, Unmatched Resource Selection Studies, Robert Clark, Tanya Strevens
Robert Clark
Studies which measure animals’ positions over time are a vital tool in understanding the process of resource selection by animals. By comparing a sample of locations that are used by animals with a sample of available points, the types of locations that are preferred by animals can be analysed by using logistic regression. Random-effects logistic regression has been proposed to deal with the repeated measurements that are observed for each animal, but we find that this is not feasible in studies where the sample of available points cannot readily be matched to specific animals. Instead, we investigate the use of …
Sampling Of Subpopulations In Two-Stage Surveys, Robert Clark
Sampling Of Subpopulations In Two-Stage Surveys, Robert Clark
Robert Clark
Many health and other surveys aim to produce statistics on small subpopulations, such as specific ethnic groups or the indigenous population of a country. In most countries, there is no reliable sampling frame of the subpopulations of interest, hence it is necessary to sample from the general population, which can be very expensive. A range of issues and strategies for sampling rare subpopulations is reviewed. The most common approaches in practice are the use of a large screening sample, and disproportionate sampling by strata. Optimal sample designs have been derived for the case of one-stage sampling, but most household interview …
Sampling For Subpopulations In Household Surveys With Application To Maori And Pacific Sampling, Robert Clark, Michael Doherty, Angela Forbes, Robert Templeton
Sampling For Subpopulations In Household Surveys With Application To Maori And Pacific Sampling, Robert Clark, Michael Doherty, Angela Forbes, Robert Templeton
Robert Clark
Many NZ national household surveys have a requirement to produce statistics with adequate precision both for the whole of NZ and for important subpopulations, particularly the Maori and Pacific populations. General population surveys which make no special provision for these groups would generally not achieve sufficient precision for Maori and Pacific estimates when these are of particular interest. Kalton and Anderson (1986) described a range of strategies for sampling subpopulations, where the aim is only to produce statistics about the subpopulation and not national statistics. The purpose of this Official Statistics Research fund project is to extend the methods of …