Point-Counting Technique for Fission-Track Dating of Tephra Glass Shards, and Its Relative Standard Error

1999 ◽  
Vol 51 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Giulio Bigazzi ◽  
Rex F. Galbraith

AbstractFission-track dating of glass is potentially an efficient technique for tephrochronological studies. However, most glasses from Quaternary tephra have very low spontaneous track densities and track counting is laborious. The point-counting technique is a simplified procedure for evaluating fission-track areal densities in a glass shard population that allows the analyst to count larger numbers of tracks in significantly shorter times. A field of view is coded as 1 if its center is on glass and is 0 otherwise, and the total area of glass is estimated by counting the number of 1's. Under simple assumptions, the binomial distribution appears to provide a reasonable evaluation of the additional experimental error in a fission-track density determination by this technique. Glass shard populations have been simulated, assuming that glass areas are random samples from distributions analogous to real ones. The effect of variation in glass area on the relative standard error of the estimated track density is found to be small. The point-counting technique significantly enhances the potential of fission-track dating, especially for very low track densities typical of most Quaternary tephra, as the additional error associated with its use is largely counterbalanced by the greater number of tracks that can be counted.

2009 ◽  
Vol 9 (1) ◽  
pp. 39-55
Author(s):  
Dennis Peque ◽  

This study was conducted in Compartment 2012a in Bosinghausen Forest District in Germany covering an area of 5 hectared. Twenty two sampling plots were laid out in the field following systematic sampling design. Results showed that all estimates for all variables (e.g. tree heights, DBH, stem density, basal area and volume) under trees that were marked for cutting have higher relative standard error. This was due to higher dispersion of individual estimates in each plot. On the other hand, the simulation study shows that sampling efficiency can be acheived by increasing the sample size. When more samples are included, the relative standard error becomes low. From this study, it can be concluded that the variability of the estimates were affected by sample size and the variability of individual units in the population or the individual esitmates (in this case, estimates in each plot).


1964 ◽  
Vol s3-105 (72) ◽  
pp. 503-517
Author(s):  
A. DOUGLAS HALLY

Several methods are available for estimating the relative volume of a tissue component from a study of tissue sections. These methods are all based on the fact that the mean relative area of a component in a series of random sections through a tissue is a consistent estimate of its relative volume in the whole tissue. Thus the problem is basically one of measuring area in a section, which can be done by the following simple counting method. The method consists of placing a regular pattern of points in the form of a square lattice upon the section image, and counting the number of points over the section N, and over the component n Relative area of component ≑n/N The method also measures absolute ares, and where d is the distance between adjacent points, absolute area of component ≑nd2 This capacity to measure absolute area means that the method is particularly suitable for determining a component which has a low relative volume. The accuracy of the method is influenced by several factors including the size of the grid mesh, and the relative area, shape, and spatial arrangment of the component. With reasonable care the error will not be larger than that of a truly randon system of points, as expressed by the following: relative standard error ≑√(1-p)/√n, where p is the relative area of the component, and the relative standard error (R.S.E.) is S.E./relative area of component. The method is equallyapplicable to either light or electron microscopy. A series of measurements on electron micrographs of rat cardiac muscle revealed a close agreement between the counting method and planimetry. The method is rapid, simple and accurate, and requres no complex apparatus.


2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Vito Di Bona

Abstract The Fetal–Infant mortality rate (FIMR) is the basic surveillance statistic in perinatal periods of risk (PPOR) analyses. This paper presents a model for the FIMR as the ratio of two Poisson random variables. From this model, expressions for estimators of variance, standard error, and relative standard error are developed. The coverage properties of interval estimators for the FIMR are investigated in a simulation study for both small and large populations and FIMR rates. Results from these studies are applied to a PPOR analysis of NC vital records. Results suggest that the sample size guidance provided in the literature to ensure statistical reliability is overly conservative and interval construction methodology should be selected based on population size.


1979 ◽  
Vol 3 (3) ◽  
pp. 93-99 ◽  
Author(s):  
Noye M. Johnson ◽  
Victor E. McGee ◽  
Charles W. Naeser

2008 ◽  
Vol 59 (7) ◽  
Author(s):  
S. S. Mitic ◽  
V. V. Zivanovic ◽  
G. Z. Miletic ◽  
D. A. Kostic ◽  
I. D. Rasic

A kinetic method for the determination of dinitrophenol is proposed. The method is based on the inhibiting effect of 2,4-dinitrophenol on the Mn(II) catalysis of the oxidation of malachite green with potassium periodate. The reaction was monitored spectrophotometrically at 615 nm. Kinetic expressions for the reaction are postulated. The optimal experimental conditions for the determination of 2,4-dinitrophenol were established and 2,4-dinitrophenol was determined in concentrations from 0.092-0.92 mg . mL-1 with relative standard error of 5.9 %. Detection limit is 0.014 mg . mL-1. The selectivity of the method is appropriate. The method was applied for the determination of dinitrophenol in urine and river water.


Author(s):  
Ashutosh ◽  
B. B. Khare ◽  
S. Khare

In this paper, we have proposed a two phase sampling estimator for domain mean using auxiliary character with unknown X a domain mean. Also discussed properties of the proposed estimator for domain mean ps a T ,γ , using auxiliary character. Simulation study of the proposed estimator ps a T ,γ , has been made with conventional ratio synthetic estimator for domain mean ps a T ,−1, using auxiliary character in terms of simulated relative standard error (SRSE) and absolute relative bias (ARB). Simulation study shows that under synthetic assumption proposed estimator is more efficient than conventional ratio synthetic estimator for domain mean using auxiliary character.  


2020 ◽  
Vol 2019 (1) ◽  
pp. 84-92
Author(s):  
Azka Ubaidillah

Pendugaan area kecil (SAE) dewasa ini berkembang cukup pesat seiring dengan meningkatnya kebutuhan atas penyediaan statistik yang terpercaya di area kecil, yaitu area dengan jumlah contoh (sampel) yang sedikit atau tidak mencukupi untuk dilakukan pendugaan secara langsung. Metode SAE dapat meningkatkan efektivitas contoh dengan “meminjam” kekuatan dari informasi area yang bertetanggaan dan pengaruh peubah penyertanya. Dalam aplikasinya, model Fay-Herriot menggunakan pendekatan Empirical Best Linear Prediction (EBLUP) banyak dilakukan karena sifat modelnya yang sederhana. Salah satu sifat sederhana dari model EBLUP adalah penggunaan hubungan linier antara peubah yang diamati dengan peubah penyertanya. Namun sering dijumpai bahwa hubungan linier tersebut belum cukup untuk meningkatkan efisiensi model SAE sebagai akibat pola yang terbentuk antara peubah amatan dan peubah penyertanya tidak linier. Paper ini menjelaskan salah satu alternatif cara untuk meningkatkan efisiensi model SAE dengan menerapkan model regresi threshold. Dari hasil simulasi dan aplikasi data pengeluaran perkapita makanan tingkat kabupaten/kota di Jawa Tengah tahun 2015 diperoleh keterangan bahwa model regresi threshold menghasilkan pendugaan dengan RMSE (root mean square error) dan RSE (relative standard error) yang lebih kecil dibandingkan model EBLUP. Hal ini menunjukkan bahwa penerapan model regresi threshold mampu untuk meningkatkan efisiensi dalam pendugaan area kecil.


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