Letter-cluster Sampling and Nominal Record Linkage

1994 ◽  
Vol 6 (3) ◽  
pp. 168-177 ◽  
Author(s):  
Sarah Richardson
Keyword(s):  
Record Linkage ◽  
Reliable Method ◽  
Cluster Sampling ◽  
Large Populations ◽  
Selection Parameter

Letter-cluster samplinghas been promoted as a reliable method of sampling large populations whilst retaining the possibility of linking them together using nominal information. This article argues that letter-cluster sampling is neither a statistically valid nor a practical technique when applied to poll books. These sources have a high correlation between the cluster-selection parameter and the parameter to be evaluated — i.e. surname and vote.

The Use of Medical Record Linkage for Population and Genetic Studies

1969 ◽  
Vol 08 (01) ◽  
pp. 07-11 ◽  
Author(s):  
H. B. Newcombe
Keyword(s):  
Record Linkage ◽  
Large Scale ◽  
Medical Record Linkage ◽  
Canadian Province ◽  
Genetic Studies ◽  
Parental Characteristics ◽  
Family Histories ◽  
The Family ◽  
Large Populations ◽  
Machine Readable

Methods are described for deriving personal and family histories of birth, marriage, procreation, ill health and death, for large populations, from existing civil registrations of vital events and the routine records of ill health. Computers have been used to group together and »link« the separately derived records pertaining to successive events in the lives of the same individuals and families, rapidly and on a large scale. Most of the records employed are already available as machine readable punchcards and magnetic tapes, for statistical and administrative purposes, and only minor modifications have been made to the manner in which these are produced.As applied to the population of the Canadian province of British Columbia (currently about 2 million people) these methods have already yielded substantial information on the risks of disease: a) in the population, b) in relation to various parental characteristics, and c) as correlated with previous occurrences in the family histories.

scholarly journals Conditions required for the attainment of colony-type stability of Neisseria gonorrhoeae in liquid culture

1975 ◽  
Vol 2 (5) ◽  
pp. 387-390
Author(s):  
E J Hart ◽  
I D Goldberg
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Liquid Medium ◽  
Liquid Culture ◽  
Reliable Method ◽  
Prolonged Incubation ◽  
Colony Type ◽  
Colony Forming Units ◽  
Large Populations

Colony-type morphology in Neisseria gonorrhoeae is associated with virulence, transformability, and the presence or absence of pili. A reliable method for achieving large populations of cells that are relatively stable with respect to colony type would be valuable, for example, in studies of virulence or for the isolation of pilus-specific phages. Previously described methods designed to achieve type stability in liquid culture were inadequate for a variety of reasons, including their low final cell yields and/or their requirements for prolonged incubation. The success of the procedure described in this communication depends upon the use of an overnight plate harvest to insure a relatively large and stable inoculum for the liquid medium. Yields of as high as 10(10) colony-forming units/ml are routinely obtained after 4 to 5 h of incubation. Such cultures exhibit a colonial-type stability of 85 to 95% with respect to the original colonial type used for inoculation of the start plate.

scholarly journals Assessment of the Effect of Six Methods of Analysis and Different Sample Sizes for Biomass Estimation in Grasslands of the State of Puebla, Mexico

Land ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1194
Author(s):  
Efraín Velasco-Bautista ◽  
Martin Enrique Romero-Sanchez ◽  
David Meza-Juárez ◽  
Ramiro Pérez-Miranda
Keyword(s):  
Sample Size ◽  
Estimation Methods ◽  
Biomass Estimation ◽  
Random Pattern ◽  
Cluster Sampling ◽  
Total Biomass ◽  
Sample Sizes ◽  
Sampling Errors ◽  
Two Stage ◽  
Large Populations

In the assessment of natural resources, such as forests or grasslands, it is common to apply a two-stage cluster sampling design, the application of which in the field determines the following situations: (a) difficulty in locating secondary sampling units (SSUs) precisely as planned, so that a random pattern of SSUs can be identified; and (b) the possibility that some primary sampling units (PSUs) have fewer SSUs than planned, leading to PSUs of different sizes. In addition, when considering the estimated variance of the various potential estimators for two-stage cluster sampling, the part corresponding to the variation between SSUs tends to be small for large populations, so the estimator’s variance may depend only on the divergence between PSUs. Research on these aspects is incipient in grassland assessment, so this study generated an artificial population of 759 PSUs and examined the effect of six estimation methods, using 15 PSU sample sizes, on unbiased and relative sampling errors when estimating aboveground, belowground, and total biomass of halophytic grassland. The results indicated that methods 1, 2, 4, and 5 achieved unbiased biomass estimates regardless of sample size, while methods 3 and 6 led to slightly biased estimates. Methods 4 and 5 had relative sampling errors of less than 5% with a sample size of 140 when estimating total biomass.

Quantitative Diameter Measurements of Chromatin and TMV Fibers in the Freeze-Dried State

1988 ◽  
Vol 46 ◽  
pp. 170-171
Author(s):  
B. D. Athey ◽  
A. L. Stout ◽  
M. F. Smith ◽  
J. P. Langmore
Keyword(s):  
Reliable Method ◽  
Fiber Diameter ◽  
Quantitative Agreement ◽  
One Dimension ◽  
Fiber Axis ◽  
Two Dimensional ◽  
Fiber Density ◽  
Variable Diameter ◽  
Freeze Dried ◽  
Expected Values

Although there is general agreement that Inactive chromosome fibers consist of helically packed nucleosomes, the pattern of packing is still undetermined. Only one of the proposed models, the crossed-linker model, predicts a variable diameter dependent on the length of DNA between nucleosomes. Measurements of the fiber diameter of negatively-stained and frozen- hydrated- chromatin from Thyone sperm (87bp linker) and Necturus erythrocytes (48bp linker) have been previously reported from this laboratory. We now introduce a more reliable method of measuring the diameters of electron images of fibrous objects. The procedure uses a modified version of the computer program TOTAL, which takes a two-dimensional projection of the fiber density (represented by the micrograph itself) and projects it down the fiber axis onto one dimension. We illustrate this method using high contrast, in-focus STEM images of TMV and chromatin from Thyone and Necturus. The measured diameters are in quantitative agreement with the expected values for the crossed-linker model for chromatin structure

Morphogenetic machines revealed: Microscopy of living cells in the embryo of the frog, Xenopus laevis

1993 ◽  
Vol 51 ◽  
pp. 172-173
Author(s):  
Ray Keller
Keyword(s):  
Image Processing ◽  
Fluorescent Dyes ◽  
Cell Movement ◽  
Living Cells ◽  
Ease Of Use ◽  
Low Light ◽  
Amphibian Embryo ◽  
Large Populations ◽  
Light Fluorescence ◽  
Video Image Processing

The amphibian embryo offers advantages of size, availability, and ease of use with both microsurgical and molecular methods in the analysis of fundamental developmental and cell biological problems. However, conventional wisdom holds that the opacity of this embryo limits the use of methods in optical microscopy to resolve the cell motility underlying the major shape-generating processes in early development.These difficulties have been circumvented by refining and adapting several methods. First, methods of explanting and culturing tissues were developed that expose the deep, nonepithelial cells, as well as the superficial epithelial cells, to the view of the microscope. Second, low angle epi-illumination with video image processing and recording was used to follow patterns of cell movement in large populations of cells. Lastly, cells were labeled with vital, fluorescent dyes, and their behavior recorded, using low-light, fluorescence microscopy and image processing. Using these methods, the details of the cellular protrusive activity that drives the powerful convergence (narrowing)

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