scholarly journals Jack knifing for semivariogram validation

Bragantia ◽  
2010 ◽  
Vol 69 (suppl) ◽  
pp. 97-105 ◽  
Author(s):  
Sidney Rosa Vieira ◽  
José Ruy Porto de Carvalho ◽  
Antonio Paz González
Keyword(s):  
Correlation Coefficient ◽  
Square Root ◽  
Trend Surface ◽  
Strong Trend ◽  
Function Fitting ◽  
Mean And Variance ◽  
The Mean ◽  
The Difference ◽  
Distinct Field ◽  
The Ideal

The semivariogram function fitting is the most important aspect of geostatistics and because of this the model chosen must be validated. Jack knifing may be one the most efficient ways for this validation purpose. The objective of this study was to show the use of the jack knifing technique to validate geostatistical hypothesis and semivariogram models. For that purpose, topographical heights data obtained from six distinct field scales and sampling densities were analyzed. Because the topographical data showed very strong trend for all fields as it was verified by the absence of a sill in the experimental semivariograms, the trend was removed with a trend surface fitted by minimum square deviation. Semivariogram models were fitted with different techniques and the results of the jack knifing with them were compared. The jack knifing parameters analyzed were the intercept, slope and correlation coefficient between measured and estimated values, and the mean and variance of the errors calculated by the difference between measured and estimated values, divided by the square root of the estimation variances. The ideal numbers of neighbors used in each estimation was also studied using the jack knifing procedure. The jack knifing results were useful in the judgment of the adequate models fitted independent of the scale and sampling densities. It was concluded that the manual fitted semivariogram models produced better jack knifing parameters because the user has the freedom to choose a better fit in distinct regions of the semivariogram.

A quantitative measure of nonlinearity

1993 ◽  
Vol 39 (5) ◽  
pp. 766-772 ◽  
Author(s):  
K Emancipator ◽  
M H Kroll
Keyword(s):  
Analytical Method ◽  
Response Curve ◽  
Polynomial Regression ◽  
Quantitative Measure ◽  
Square Root ◽  
Straight Line ◽  
The Mean ◽  
The Difference ◽  
Definition Of ◽  
Fitting In

Abstract Quantitative measures of the nonlinearity of an analytical method are defined as follows: the "(dimensional) nonlinearity" of a method is the square root of the mean of the square of the deviation of the response curve from a straight line, where the straight line is chosen to minimize the nonlinearity. The "relative nonlinearity" is defined as the dimensional nonlinearity divided by the difference between the maximum and minimum assayed values. These definitions may be used to develop practical criteria for linearity that are still objective. Calculation of the nonlinearity requires a method of curve-fitting. In this article, we use polynomial regression to demonstrate calculations, but the definition of nonlinearity also accommodates alternative nonlinear regression procedures.

Study on Records of the Wenchuan MW 8.0 Strong Earthquake in 2008

2012 ◽  
Vol 446-449 ◽  
pp. 2371-2374
Author(s):  
En Guo ◽  
Xi Yuan Zhou ◽  
Zuo Zhou Zhao ◽  
Hang Sun
Keyword(s):  
Wenchuan Earthquake ◽  
Correlation Coefficient ◽  
Strong Earthquake ◽  
Strong Motion ◽  
Perpendicular Direction ◽  
Classification Analysis ◽  
Near Fault ◽  
The Mean ◽  
The Difference

There are a large number of acceleration records obtained in the near fault strong motion of Wenchuan earthquake in 2008, which greatly enriched the database of strong motion. By the classification analysis to Sichuan records and comparison with the domestic and international earthquakes analysis, we draw the following conclusions: 1) whether parallel or perpendicular direction, the peaks of soil are greater than rock. With the fault distance increasing, the gap between the two gradually will minish.2) With the increase in the number of peaks obtained, the correlation coefficient of GPGA or LGPA is generally increasing.3) The mean of R is respectively 8.10(rock), 10.31(soil), 10.10(total) in the usual range.4). The average of λ is respectively 0.5862(rock), 0.5707(soil), 0.5722(total), they are between 1/2 and 2/3. The difference is not large.

scholarly journals Evaluation of the New Digital Goldmann Applanation Tonometer for Measuring Intraocular Pressure

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Yuta Sakaue ◽  
Jun Ueda ◽  
Masaaki Seki ◽  
Takayuki Tanaka ◽  
Tetsuya Togano ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Correlation Coefficient ◽  
Pearson’S Correlation ◽  
Pearson’S Correlation Coefficient ◽  
Goldmann Applanation Tonometer ◽  
Applanation Tonometer ◽  
Pearson's Correlation ◽  
The Mean ◽  
The Difference ◽  
Pearson's Correlation Coefficient

Purpose. To compare a new digital Goldmann applanation tonometer (dGAT) that measures intraocular pressure (IOP) in 0.1 mmHg increments to a standard Goldmann applanation tonometer (sGAT).Methods. This study included 116 eyes of 60 subjects. A single examiner first measured IOP in triplicate using either sGAT or dGAT, which was randomly chosen. After a 5-minute interval, the next set of three consecutive IOP was measured using the other GAT.Results. The mean IOP measured with sGAT was 16.27 ± 6.68 mmHg and 16.35 ± 6.69 mmHg with dGAT. Pearson’s correlation coefficient was 0.998 (P<0.01). The subjects were divided into three groups based on the mean IOP: IOP < 14 mmHg, 14–20 mmHg, or >20 mmHg. The Pearson’s correlation coefficient within each group was 0.935, 0.972, and 0.997 (P<0.01), respectively. The difference within the three consecutive IOP measurements (maximum–minimum) for dGAT (0.72 ± 0.34 mmHg) was significantly smaller than those with sGAT (0.92 ± 0.42 mmHg,P<0.01). Even in patients with equal IOP (zero left-right difference) with sGAT (n=30), dGAT detected IOP differences between the left and right eyes (0.47 ± 0.31 mmHg).Conclusion. Compared to sGAT, dGAT measurements are highly reproducible and less variable.

scholarly journals Relationship between Students’ Achievement in Essay and Practical Tests on Biology in Nsukka Education Zone

2020 ◽  
pp. 42-46
Author(s):  
Ifeanyi I. Adonu ◽  
Ekene H. Obiora
Keyword(s):  
Correlation Coefficient ◽  
Research Question ◽  
Positive Association ◽  
Biology Students ◽  
The Mean ◽  
Research Questions ◽  
The Difference ◽  
Essay Tests ◽  
The Relationship ◽  
Evaluation Techniques

This study investigated the relationship between students’ achievement in practical and essaytests on biology. Two research questions were formulated- (i) what is the difference in the mean score of students in practical and essay tests in mock biology examinations? (ii) what is the measure of relationship (correlation coefficient) of students’ achievement in practical and essay aspects of biology tests? The research was conducted among public secondary schools in Nsukka Education Zone of Enugu State with a sampled population of 560 biology students (321 males and 239 females) from randomly sampled schools from the three local government areas in the zone.The Correlation survey research design was adopted for this study and the instrument of data collection were the results of the 2018 students’ mock practical and theoretical tests on biology from the sampled schools.The data collected were analysed using Descriptive statistics (mean and standard deviation) for research question 1, while the Pearson Product-Moment Correlation Coefficient analysis was used for research question 2. The findings of the study revealed that a weak positive association existed between the students’ achievementin practical and essay biology tests. So, the achievement in one aspect does not in any way influence the achievement in the other. The study thus recommends that: (1) teachers should have good mastery and evaluation techniques of all components of biology so that students would approach them with equal ability; (2) parents should encourage the students to develop interest and ability in the different components of biology; and (3) government should provide and equip biology laboratories to ensure students’ utilization of same.

Research on the Grading Theory of Thick and Thin Defects in the Electronic Testing for Raw Silk

2011 ◽  
Vol 175-176 ◽  
pp. 439-444 ◽  
Author(s):  
Jian Tao Niu ◽  
Qi Hu ◽  
Jian Mei Xu ◽  
Suo Zhuai Dong ◽  
Lun Bai
Keyword(s):  
Negative Binomial ◽  
Mean And Variance ◽  
The Mean ◽  
Spot Tests ◽  
The Difference ◽  
Grading Standards ◽  
The Right ◽  
Power Law Equation ◽  
The Relationship ◽  
Electronic Detector

Based on the sampling and grading theory of raw silk test, this paper studied the grading theory method of thick and thin defects of the raw silk in the electronic testing. By means of analyzing the data obtained from the raw silk electronic detector, the fact that the thick and thin defects of the raw silk appropriately take negative binomial distribution in the electronic testing has been confirmed. Under such circumstance, the distribution of the average of the sampling samples of the thick and thin defects was given, and fitting on the relationship between the mean and variance of the thick and thin defects were carried out by introducing Taylor’s power law equation, thus the right grading rate and probability of the difference between two spot tests about the thick and thin defects of the raw silk in the electronic testing was deduced. Moreover, the conclusion of the theoretical analysis was confirmed by simulation tests. The results might provide a basis for establishing the grading standards of the thick and thin defects in the electronic testing for raw silk.

The investigations of pulsar integral radio luminosities

1996 ◽  
Vol 160 ◽  
pp. 59-60
Author(s):  
Igor’ F. Malov ◽  
Oleg I. Malov ◽  
Valerij M. Malofeev
Keyword(s):  
Mean Value ◽  
Main Mechanism ◽  
Square Root ◽  
Mean Square ◽  
Pulsar Period ◽  
Light Cylinder ◽  
Curvature Radiation ◽  
The Mean ◽  
The Difference ◽  
Integral Radio

We have calculated accurate integral radio luminositiesLfor 232 pulsars (Malov et al., 1994) using new average spectra of these objects. Histogram ofL-distribution is characterized by the mean value &lt; logL&gt;= 28.45 and by the mean-square-root deviationS= 1.0. We have analysed also data for short-periodic pulsars (P &lt; 0.1 s) and long-periodic ones (P &gt; 1 s) separately.The main goal of such separation was to test the hypothesis on two types of pulsars (Malov, 1987): i) for the first group of objects radiation is emitted from the neighbourhood of the light cylinder (r=rLC=cP/2π, P is the pulsar period), ii) for the second one emission is generated at distancesr≪rLC. In the second case the main mechanism of radiation is curvature radiation. For the first group of pulsars the radiation is connected with the cyclotron mechanism. The difference between two basic mechanisms and the locations of the emission generation regions must cause some differences in the observable features for these two classes of pulsars.

scholarly journals Long-Term Performance of Aanderaa Optodes and Sea-Bird SBE-43 Dissolved-Oxygen Sensors Bottom Mounted at 32 m in Massachusetts Bay

2007 ◽  
Vol 24 (11) ◽  
pp. 1924-1935 ◽  
Author(s):  
Marinna Martini ◽  
Bradford Butman ◽  
Michael J. Mickelson
Keyword(s):  
Dissolved Oxygen ◽  
Correlation Coefficient ◽  
Field Evaluation ◽  
Mean Difference ◽  
Massachusetts Bay ◽  
The Mean ◽  
The Difference ◽  
Long Term Performance ◽  
Term Performance ◽  
Oxygen Measurements

Abstract A field evaluation of two new dissolved-oxygen sensing technologies, the Aanderaa Instruments AS optode model 3830 and the Sea-Bird Electronics, Inc., model SBE43, was carried out at about 32-m water depth in western Massachusetts Bay. The optode is an optical sensor that measures fluorescence quenching by oxygen molecules, while the SBE43 is a Clark polarographic membrane sensor. Optodes were continuously deployed on bottom tripod frames by exchanging sensors every 4 months over a 19-month period. A Sea-Bird SBE43 was added during one 4-month deployment. These moored observations compared well with oxygen measurements from profiles collected during monthly shipboard surveys conducted by the Massachusetts Water Resources Authority. The mean correlation coefficient between the moored measurements and shipboard survey data was &gt;0.9, the mean difference was 0.06 mL L−1, and the standard deviation of the difference was 0.15 mL L−1. The correlation coefficient between the optode and the SBE43 was &gt;0.9 and the mean difference was 0.07 mL L−1. Optode measurements degraded when fouling was severe enough to block oxygen molecules from entering the sensing foil over a significant portion of the sensing window. Drift observed in two optodes beginning at about 225 and 390 days of deployment is attributed to degradation of the sensing foil. Flushing is necessary to equilibrate the Sea-Bird sensor. Power consumption by the SBE43 and required pump was 19.2 mWh per sample, and the optode consumed 0.9 mWh per sample, both within expected values based on manufacturers’ specifications.

On the mean and variance of the tetrachoric correlation coefficient

Psychometrika ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 347-355 ◽  
Author(s):  
Morton B. Brown ◽  
Jacqueline K. Benedetti
Keyword(s):  
Correlation Coefficient ◽  
Tetrachoric Correlation ◽  
Mean And Variance ◽  
The Mean

scholarly journals SELF-CONCEPT, ATTITUDE AND PERCEPTION OF USEFULNESS OF PHYSICS AND CHEMISTRY ACCORDING TO TYPE AND LOCATION OF SCHOOLS

2016 ◽  
pp. 218-233
Author(s):  
Inzahuli Samuel Majere ◽  
Elizabeth Role ◽  
Lazarus Ndiku Makewa
Keyword(s):  
Correlation Coefficient ◽  
Positive Attitude ◽  
T Test ◽  
Rural Students ◽  
Self Concept ◽  
Single Sex ◽  
Significant Difference ◽  
The Mean ◽  
The Difference ◽  
Type Of School

This study was an attempt to test if students differed in their self-concept, attitude and their perception of the usefulness of Physics and Chemistry in terms of their type of school and location. To test this hypothesis, t-test was used to compare differences in the mean scores in terms of type of school and location. Pearson's Product Moment Correlation coefficient was used to determine the relationships between independent and dependent variable. Four hundred and forty six (446) students constituted the sample. The attitude towards Physics and Chemistry and the perception of the type of school showed there was no significant difference between single-sex and co- educational school. There was no significant difference between single- sex and co- educational school (mixed) students in their self- concept in Physics and Chemistry. There was no significant difference between single- sex and co- educational school (mixed) students in their perception of the usefulness of Physics and Chemistry. Results also show that urban students have better perception of the usefulness of Physics and Chemistry than the rural students. The difference in perception of the usefulness of Chemistry is statistically significant but the difference in perception of the usefulnessofPhysicsisnotstatisticallysignificant. Bothruralandurbanstudentshad positive attitude and self-concept for Physics and Chemistry.

Sign in / Sign up

Export Citation Format

Share Document