Showing papers on "Sampling (statistics) published in 1976"

Network Sampling: Some First Steps

Abstract: Social network research has been confined to small groups because large networks are intractable, and no systematic theory of network sampling exists. This paper describes a practical method for sampling average acquaintance volume (the average number of people known by each person) from large populations and derives confidence limits on the resulting estimates. It is shown that this average figure also yields an estimate of what has been called "network density." Applications of the procedure to community studies, hierarchical structures, and interorganizational networks are proposed. Problems in developing a general theory of network sampling are discussed.

Statistical Analysis of Spatial Point Patterns by Means of Distance Methods

Abstract: Summary Various distance-based methods of testing for randomness in a population of spatially distributed events are described. Special emphasis is placed upon preliminary analysis in which the complete enumeration of the events within the study area is not available. Analytical progress in assessing the power of the techniques against extremes of aggregation and regularity is reviewed and the results obtained from the Monte Carlo simulation of more realistic processes are presented. It is maintained that the method of T-square sampling can help to provide quick and informative results and is especially suited to large populations. Some comments on contiguous quadrat methods are made.

The Linear Least-Squares Prediction Approach to Two-Stage Sampling

Abstract: The linear least-squares prediction approach is applied to some problems in two-stage sampling from finite populations A theorem giving the optimal (BLU) estimator and its error-variance under a general linear “superpopulation” model for a finite population is stated This theorem is then applied to a model describing many populations whose elements are grouped naturally in clusters Next, the probability model is used to analyze various conventional estimators and certain estimators suggested by the theory as alternatives to the conventional ones Problems of design are considered, as are some consequences of regression-model failure

Network design for the estimation of areal mean of rainfall events

Abstract: This work recognizes rainfall as a multidimensional stochastic process. By using the knowledge of such processes and of multivariate estimation theory a procedure for designing an optimal network to obtain the areal mean precipitation of an event over a fixed area is developed. The methodology used in this problem allows consideration of the following aspects of network design: (1) spatial uncertainty and correlation of process, (2) errors in measurement techniques and their correlation, and (3) non-homogeneous sampling costs. Optimal networks are given in terms of the number and location of stations together with the resulting cost and mean square error of rainfall estimation.

Ecosystem Persistence and Heterotrophic Regulation

Abstract: Mechanisms leading to ecosystem persistence are explored with a simple mathe- matical conceptualization. The concept is quantified for six ecosystems ranging from tundra to tropics and including both terrestrial and aquatic systems. Deductions from the concept are compared with predictions from the theory of power as a basic parameter of system function. Analysis of the equations indicates that heterotrophs in the ecosystem may be capable of exerting effective control by changes in biomass that would be difficult to detect in field sampling. The effectiveness of the control is influenced by significant differences in turnover rates among ecosystem components. It is suggested that simple mathematical constructs, quantifiable from available data and amenable to direct analysis, have much to offer in increasing our understanding of ecosystem function.

Multiple deferred state sampling inspection

Abstract: Multiple deferred state sampling is on attribute inspection procedure in which the decision criterion for each lot dictates one of three decisions: (1) accept the lot; (2) reject the lot; or (3) conditionally accept or reject the lot based on the disposition of future related lots. It is intended to supplement existing sampling procedures such as chain sampling, dependent stage sampling, exponential smoothed sampling, and fixed deferred state sampling.

Land-use map accuracy criteria

Abstract: In generating maps to meet prescribed accuracy standards from remote sensing data, validation is required. Cost considerations dictate that a sampling strategy for field checking be employed. The use of a sampling procedure to assess the accuracy of polygon classification, boundary line placement, and control point placement on land-use maps is described. Combining these measures into a single figure of merit with a confidence interval is suggested to foster acceptance in the user community.

Statistical quality control methods

Abstract: Why Statistics? Characteristics of Data and How to Describe Them. Simple Probability Three Basic Laws for Attribute Data Control Charts in General Control Charts for Attributes: Process Control Control Charts for Measurements: Process Control Further Topics in Control Charts and Applications Acceptance Sampling for Attributes Some Standard Sampling Plans for Attributes Sampling by Variables Tolerances for Mating Parts and Assemblies Studying Relationships Between Variables by Linear Correlation and Regressions A Few Reliability Concepts

Chromospheric Variations in Main Sequence Stars

Abstract: The work described here is still in progress; hence this paper will be a brief sampling of the results to date.

Surficial Sediments of Lake Erie

Abstract: On the basis of extensive echosounding and grab sampling, three major units have been recognized in Lake Erie: till and bedrock, glaciolacustrine clay, and postglacial muds. These units represent t...

Sampling and Smoothing of Spectra

Abstract: Anyone working with a spectrometer or similar system should be concerned with using it in the best possible way. This article is concerned with a portion of that problem, viz., the acquisition and treatment of the data. We describe herein what is going on in these various processes and show the dependence of various phenomena on the important parameters. On the basis of the evidence, we then recommend certain procedures and suggest appropriate values for the parameters involved.

The Use of Balanced Half-Sample Replication in Cross-Validation Studies

Abstract: Cross-validation techniques involve omitting a portion of the available data, fitting a prediction function to the portion remaining, and then testing the fitted function on the omitted data. Ideally, one would like to repeat this process on all possible splits. In many instances, this is not computationally feasible. This paper argues and demonstrates, using half samples by way of illustration, that the balanced sampling techniques developed for the analysis of complex sample survey data provide an efficient way of sampling the population of all possible splits.

Species enrichment due to Mach‐number focusing in a molecular‐beam mass‐spectrometer sampling system

Abstract: The analysis and measurements reported here emphasize the need to take into account species enrichments due to Mach‐number focusing when sampling gas mixtures using a molecular‐beam mass‐spectrometer sampling system. Depending upon source conditions and system geometry, the enrichment of a given species may vary from unity to a value which is of the order of magnitude of the ratio of the given‐species mass to the major‐species mass. Procedures for handling effects of Mach‐number focusing on species enrichments are presented. These procedures are more general than previous procedures in that they accommodate, as needed, (a) flow divergence upstream from the skimmer and (b) transition to free‐molecule flow (for one or more of the several species) upstream from the skimmer. The measurements support a procedure for handling effects of pressure diffusion near the sampling source which was suggested earlier. An empirical curve for handling modest effects of skimmer interference is included.

Correlation type gogdness-of-fit statistics with censored sampling

Abstract: Some comments are made concerning the possible forms of a correlation coefficient type goodness-of-fit statistic, and their relationship with other goodness-of-fit statistics, Critical values for a correlation goodness-of-fit statistic and for the Cramer-von Mises statistic are provided for testing a completely-specified null hypothesis for both complete and censored sampling, Critical values for a correlation test statistic are provided for complete and censored sampling for testing the hypothesis of normality, two parameter exponentiality, Weibull (or, extreme value) and an exponential-power distribution, respectively. Critical values are also provided for a test of one-parameter exponentiality based on the Cramer-von Mises statistic

Manual of methods in aquatic environment research. Part 3 - Sampling and analyses of biological material (guidelines for the FAO(GFCM)/UNEP Joint Coordinated Project on Pollution in the Mediterranean)

Abstract: Manual of methods in aquqtic environment research. part 3, sampling and analyses of biological material (Guidelines for the FAO (GFCM)/UNEP joint coordinated project on pollution in the Mediterranean , Manual of methods in aquqtic environment research. part 3, sampling and analyses of biological mater... , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Further applications of bias to discriminant analysis

Abstract: This article extends the biased minimum x2 rule to the unequal covariance matrix case and to the case of several populations, The biased procedure is shown to improve the performance of the commonly used classification procedures. Results of sampling experiments over a broad range of conditions are provided to demonstrate this improvement.

Long-Distance Transport of 2,4-D.

Abstract: Ambient 2,4-D herbicide concentrations in south-central Washington's grape growing areas can reach damaging levels due to aerial 2,4-D applications to wheat fields tens of miles removed from the affected areas. An atmospheric 2,4-D sampling study was conducted by WSU during the spring months of 1973 and 1974. Eight 2,4-D sampler sites were operated on a more or less continuous basis from April through mid-June. Meteorological conditions accompanying day-to-day concentration patterns were analyzed. Results showed that weak frontal systems characterized by mid-level cloudiness and light prefrontal southerly surface winds accompanied higher concentration periods. Conversely, lower concentration periods were accompanied by quasi-stationary high-pressure systems or weak thermally induced low-pressure system.

Rainfall network design for runoff prediction

Abstract: A multivariate state-space stochastic model of rainfall based on a multidimensional rainfall generator suggested by Bras and Rodriguez-Iturbe (1976a) is used together with a runoff model to study the accuracy of discharge prediction as a function of the rainfall-sampling network. The runoff model used is a spatially distributed simulation based on a finite difference solution of the kinematic wave equations. Discharge prediction accuracy at any point in a basin can be obtained in terms of the mean square error as a function of the number of rain-sampling stations, their location, and the errors in sampling devices. The solution is also a function of the physics of the basin at hand which is incorporated in the rainfall-runoff model. The mean square error of discharge estimation is obtained by using linear estimation theory for dynamic systems. Particularly, the technique used is the Kalman-Bucy filter, which permits filtering and extrapolation of noisy and incomplete observations.

Methods for obtaining drug time course data from individual small laboratory animals: serial microblood sampling and assay.

Abstract: (1976). Methods for Obtaining Drug Time Course Data from Individual Small laboratory Animals: Serial Microblood Sampling and Assay. Drug Metabolism Reviews: Vol. 5, No. 2, pp. 295-310.

Sampling from the gamma distribution on a computer

Abstract: This paper describes a method of generating gamma variates that appears to be less costly than Wallace's recently suggested method. For large shape parameter a; the cost of computation is proportional to √a, whereas Wallace's method is proportional to a. Experimentation by Robinson and Lewis indicates that for small a the method suggested here also dominates methods recently suggested by Dieter and Ahrens, albeit those methods dominate for large a. The method suggested here uses the rejection technique.

On Unequally Spaced Time Points in Time Series

Abstract: This article discusses the sampling of stationary discrete-time stochastic processes at fixed but unequally spaced time points. The pattern of the sampling times is periodic with a cycle of $p$ time units. One of the major problems is to determine given $p$ the minimum number of sampling points required per cycle in order to estimate the covariances at all lags. The second problem is to find a pattern of distribution for the sampling points within the cycle which will allow the estimation of all covariances. A discussion of the references which describe the statistical properties of the estimates of covariances and spectra in this sampling situation is given.

Color imaging array

Abstract: Light responsive elements of a color imaging array are arranged in basic groupings of four aligned elements, which groupings included two luminance-responsive elements that alternate with individual elements for two other basic colors These groupings are repeated along a line and are shifted by one element in each adjacent line As a result of intermixing color-responsive elements in this way, high-spatial-frequency luminance sampling is achieved for all directions on the array and closely repeated patterns of elements are achieved for all three basic colors in both fields of the array (here assuming a two-field interlaced readout array) Because closely repeated sampling occurs for all colors in both fields of such an array, the field-to-field color flicker, that can occur when intermixed color sampling is attempted using an interlaced-readout imaging array, is avoided