scholarly journals A Comparison Of Usual t-Test Statistic and Modified t-Test Statistics on Skewed Distribution Functions

2016 ◽  
Vol 15 (2) ◽  
pp. 67-89 ◽  
Author(s):  
Wooi K. Lim ◽  
Alice W. Lim
Keyword(s):  
Distribution Functions ◽  
T Test ◽  
Skewed Distribution ◽  
Test Statistics ◽  
Test Statistic

Testing for equality of means with equal and unequal variances

2021 ◽  
Vol 20 (2) ◽  
pp. 51-60
Author(s):  
A.O. Abidoye ◽  
W.A. Lamidi ◽  
M.O. Alabi ◽  
J. Popoola
Keyword(s):  
Agricultural Development ◽  
Secondary Data ◽  
Development Project ◽  
T Test ◽  
Harmonic Mean ◽  
Test Statistics ◽  
Test Statistic ◽  
Unequal Variances ◽  
Equality Of Means ◽  
Pooled Sample

In this paper, we are interested in comparing the conventional t –test with the proposed t – test for testing equality of means with unequal and equal variances. Here, we proposed harmonic mean of variances as an alternative to the pooled sample variance when there is heterogeneity of variances. Two sets of secondary data were obtained from Agricultural Development Project (KWADP) and the Ministry of Agriculture in Ilorin, Kwara State to demonstrate the two test statistics used and the results show that the proposed t – test statistic is found to be appropriate than the conventional t – test statistic when we have unequal variances but the conventional t – test perform better when we have equal variances.

scholarly journals A NOTE ON THE CONVENTIONAL OUTLIER DETECTION TEST PROCEDURES

2015 ◽  
Vol 21 (2) ◽  
pp. 433-440 ◽  
Author(s):  
JIANFENG GUO
Keyword(s):  
Outlier Detection ◽  
Goodness Of Fit ◽  
T Test ◽  
Test Statistics ◽  
Test Statistic ◽  
Test Procedures ◽  
Global Test ◽  
Normal Test ◽  
Student’S T ◽  
Student’S T Test

Under the assumption of that the variance-covariance matrix is fully populated, Baarda's w-test is turn out to be completely different from the standardized least-squares residual. Unfortunately, this is not generally recognized. In the limiting case of only one degree of freedom, all the three types of test statistics, including Gaussian normal test, Student's t-test and Pope's Tau-test, will be invalid for identification of outliers: (1) all the squares of the Gaussian normal test statistic coincide with the goodness-of-fit (global) test statistic, even for correlated observations. Hence, the failure of the global test implies that all the observations will be flagged as outliers, and thus the Gaussian normal test is inconclusive for localization of outliers; (2) the absolute values of the Tau-test statistic are all exactly equal to one, no matter whether the observations are contaminated. Therefore, the Tau-test cannot work for outlier detection in this situation; and (3) Student's t-test statistics are undefined.

scholarly journals Rounded Input Variables, Exact Test Statistics (RIVETS)

2019 ◽  
Author(s):  
Nicholas J. L. Brown ◽  
James Heathers
Keyword(s):  
Statistical Tests ◽  
T Test ◽  
Test Statistics ◽  
Test Statistic ◽  
Statistical Software ◽  
Exact Test ◽  
Manual Intervention ◽  
Software Packages ◽  
Rounded Form ◽  
Input Variables

Most statistical software packages report the input values to statistical tests (e.g., means and standard deviations for an unpaired t test) in a rounded form (e.g., to two decimal places), with this rounding having been performed after the test statistic has been calculated. However, in some cases, the input values are rounded before the test statistic is calculated, most likely because of some form of manual intervention by the researcher. We describe a method that enables the probabilistic identification of detecting this rounding, the conditions required for this method to be applicable, the tests where pre-calculation rounding can be detected, and the implications of its detection.

scholarly journals Effects of kinship correction on inflation of genetic interaction statistics in commonly used mouse populations

2021 ◽  
Author(s):  
Anna L Tyler ◽  
Baha El Kassaby ◽  
Georgi Kolishovski ◽  
Jake Emerson ◽  
Ann E Wells ◽  
...  
Keyword(s):  
Mixed Model ◽  
Linear Mixed Model ◽  
Genetic Interaction ◽  
Recombinant Inbred Lines ◽  
Test Statistics ◽  
Test Statistic ◽  
Kinship Matrix ◽  
Main Effect ◽  
Main Effects ◽  
Interaction Test

Abstract It is well understood that variation in relatedness among individuals, or kinship, can lead to false genetic associations. Multiple methods have been developed to adjust for kinship while maintaining power to detect true associations. However, relatively unstudied, are the effects of kinship on genetic interaction test statistics. Here we performed a survey of kinship effects on studies of six commonly used mouse populations. We measured inflation of main effect test statistics, genetic interaction test statistics, and interaction test statistics reparametrized by the Combined Analysis of Pleiotropy and Epistasis (CAPE). We also performed linear mixed model (LMM) kinship corrections using two types of kinship matrix: an overall kinship matrix calculated from the full set of genotyped markers, and a reduced kinship matrix, which left out markers on the chromosome(s) being tested. We found that test statistic inflation varied across populations and was driven largely by linkage disequilibrium. In contrast, there was no observable inflation in the genetic interaction test statistics. CAPE statistics were inflated at a level in between that of the main effects and the interaction effects. The overall kinship matrix overcorrected the inflation of main effect statistics relative to the reduced kinship matrix. The two types of kinship matrices had similar effects on the interaction statistics and CAPE statistics, although the overall kinship matrix trended toward a more severe correction. In conclusion, we recommend using a LMM kinship correction for both main effects and genetic interactions and further recommend that the kinship matrix be calculated from a reduced set of markers in which the chromosomes being tested are omitted from the calculation. This is particularly important in populations with substantial population structure, such as recombinant inbred lines in which genomic replicates are used.

A test for fuzzy exponentiality based on Kullback-Leibler information

2021 ◽  
pp. 1-8
Author(s):  
Lingtao Kong
Keyword(s):  
Biological Sciences ◽  
Monte Carlo ◽  
Goodness Of Fit ◽  
Experimental Studies ◽  
Real Data ◽  
Test Statistics ◽  
Test Statistic ◽  
Goodness Of Fit Test ◽  
Higher Power ◽  
Leibler Information

The exponential distribution has been widely used in engineering, social and biological sciences. In this paper, we propose a new goodness-of-fit test for fuzzy exponentiality using α-pessimistic value. The test statistics is established based on Kullback-Leibler information. By using Monte Carlo method, we obtain the empirical critical points of the test statistic at four different significant levels. To evaluate the performance of the proposed test, we compare it with four commonly used tests through some simulations. Experimental studies show that the proposed test has higher power than other tests in most cases. In particular, for the uniform and linear failure rate alternatives, our method has the best performance. A real data example is investigated to show the application of our test.

scholarly journals Pengaruh Model Pembelajaran ASSURE TERHADAP Hasil Belajar Siswa pada Materi Suhu dan Kalor

2018 ◽  
Vol 1 (1) ◽  
pp. 009-020
Author(s):  
Sunartih Sunartih ◽  
Marungkil Pasaribu ◽  
Amiruddin Hatibe
Keyword(s):  
Standard Deviation ◽  
Hypothesis Testing ◽  
Student Learning ◽  
Learning Outcomes ◽  
Student Learning Outcomes ◽  
Learning Model ◽  
T Test ◽  
Test Statistic ◽  
Model Learning ◽  
Average Value

This study aims to determine whether there is an influence of ASSURE learning model on student learning outcomes in temperature and heat material of class XI SMA. The method used is quasi-experimental with equivalent pretest-posttest design. The population of this study were all students of class XI SMA . Sampling was carried out by purposive sampling with the sample of the study being class XI Mipa 2 as the experimental class and class X1 Mipa 5 as the control class. The research instrument in the form of learning outcomes tests and observation sheets that have been validated by the validator and field tested. Data analysis used inferential statistics is normality, homogeneity, hypothesis testing (2-party t test). Based on the results of research and analysis of research data, obtained the value of student learning outcomes at posttest average value of the experimental class is 14.90 with a standard deviation of 3.23 and for the control class of 11.57 with a standard deviation of 2.99. The test results of the t test statistic of 2 parties from hypothesis testing obtained the price thitung(4,11)>ttabel(1,67) or thitung(-4,11)>ttabel(-1,67) so that H1 is accepted and H0 is rejected. This result states that there are differences in student learning outcomes in physics subjects between classes taught with the ASSURE learning model and Direct Intruction learning models. It can be concluded that there is an influence of the ASSURE learning model on student learning outcomes in temperature and heat material in class XI of SMA. Keywords: assure learning model, learning outcomes, temperature and heat  

scholarly journals PENGARUH LATIHAN TERPUSAT DAN LATIHAN ACAK TERHADAP HASIL PENGUASAAN TEKNIK DASAR BOLA BASKET

KINESTETIK ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 36-43
Author(s):  
Setiana Wati ◽  
Tono Sugihartono ◽  
Sugiyanto Sugiyanto
Keyword(s):  
Statistical Analysis ◽  
Experimental Methods ◽  
Statistical Test ◽  
T Test ◽  
Distributed Data ◽  
Statistical Calculation ◽  
Test Statistic ◽  
Basic Technique ◽  
Test Criterion ◽  
Experimental Group

Abstrak Penelitian ini bertujuan untuk mengetahui pengaruh antara latihan terpusat dan latihan acak terhadap hasil penguasaan teknik dasar bola basket. Penelitian ini menggunakan metode eksperimen yang dilakukan terhadap dua kelompok, yaitu kelompok eksperimen satu yang di beri perlakuan latihan terpusat dan kelompok eksperimen dua di beri perlakuan latihan acak. Penelitian dilakukan di Klub Basket Poltekkes Kemenkes Bengkulu dengan sampel yang di pilih berdasarkan karakteristik tertentu. Analisis statistik yang di gunakan dalam penelitian ini adalah Uji t untuk menguji hipotesis bahwa “latihan acak memberikan pengaruh lebih baik dibandingkan dengan latihan terpusat dalam meningkatkan keterampilan teknik dasar bola basket”. Uji syarat statistik t telah memenuhi syarat homogen dan data berdistribusi normal berdasarkan perhitungan statistik dan pengujian kriteria uji statistic di dapat hasil bahwa latihan terpusat dan latihan acak memberikan pengaruh terhadap hasil penguasaan teknik dasar bola basket. Hal ini diketahui dari data thitung = -5,11 > ttabel = 2,11 dengan taraf ?=0,05. Kesimpulan dari penelitian ini dilihat dari hasil uji signifikan perbedaan peningkatan latihan kedua kelompok menunjukkan bahwa latihan acak memberikan pengaruh yang lebih signifikan terhadap hasil  penguasaan teknik dasar bola basket. Kata Kunci: Latihan terpusat, Latihan acak, Teknik Dasar Bola Basket.Abstract This study aims to determine the effect of centralized training and random exercise on the results of mastery of basic techniques of basketball. This study used experimental methods conducted on two groups, namely the experimental group one which was given the treatment of centralized exercise and the experimental group of two in the treatment of random treatment. The research was conducted at Club Basket Poltekkes Kemenkes Bengkulu with selected samples based on certain characteristics. The statistical analysis used in this study is t-test to test the hypothesis that "randomized exercise gives better effect than centralized training in improving basic basketball technique skills". Test statistic requirement t has complied with homogeneous requirements and normal distributed data based on statistical calculation and statistical test criterion test in can result that centralized exercise and random exercise have an effect on the result of mastery of basic technique of basketball. It is known from thitung = -5,11> ttable = 2,11 with ? = 0,05. The conclusions of this study seen from the results of significant test differences in the improvement of the two groups showed that the random exercise gives a more significant effect on the results of mastery of basic techniques of basketball. Keywords: Centralized exercise, Random exercise, Basic Basketball Technique.

scholarly journals An approach to gene-based testing accounting for dependence of tests among nearby genes

2021 ◽  
Author(s):  
Ronald J Yurko ◽  
Kathryn Roeder ◽  
Bernie Devlin ◽  
Max G'Sell
Keyword(s):  
Multiple Testing ◽  
Association Studies ◽  
Autism Spectrum ◽  
P Value ◽  
Genome Wide Association Studies ◽  
Strongly Correlated ◽  
Test Statistics ◽  
Test Statistic ◽  
Genome Wide ◽  
Insight Into

In genome-wide association studies (GWAS), it has become commonplace to test millions of SNPs for phenotypic association. Gene-based testing can improve power to detect weak signal by reducing multiple testing and pooling signal strength. While such tests account for linkage disequilibrium (LD) structure of SNP alleles within each gene, current approaches do not capture LD of SNPs falling in different nearby genes, which can induce correlation of gene-based test statistics. We introduce an algorithm to account for this correlation. When a gene's test statistic is independent of others, it is assessed separately; when test statistics for nearby genes are strongly correlated, their SNPs are agglomerated and tested as a locus. To provide insight into SNPs and genes driving association within loci, we develop an interactive visualization tool to explore localized signal. We demonstrate our approach in the context of weakly powered GWAS for autism spectrum disorder, which is contrasted to more highly powered GWAS for schizophrenia and educational attainment. To increase power for these analyses, especially those for autism, we use adaptive p-value thresholding (AdaPT), guided by high-dimensional metadata modeled with gradient boosted trees, highlighting when and how it can be most useful. Notably our workflow is based on summary statistics.

A Bounds Approach to Inference Using the Long Run Multiplier

2019 ◽  
Vol 27 (3) ◽  
pp. 281-301 ◽  
Author(s):  
Clayton Webb ◽  
Suzanna Linn ◽  
Matthew Lebo
Keyword(s):  
Unit Root ◽  
Unit Roots ◽  
Small Sample ◽  
Stochastic Simulations ◽  
Upper And Lower Bounds ◽  
Test Statistics ◽  
Test Statistic ◽  
Independent Variables ◽  
Long Run ◽  
Presidential Success

Pesaran, Shin, and Smith (2001) (PSS) proposed a bounds procedure for testing for the existence of long run cointegrating relationships between a unit root dependent variable ($y_{t}$) and a set of weakly exogenous regressors $\boldsymbol{x}_{t}$ when the analyst does not know whether the independent variables are stationary, unit root, or mutually cointegrated processes. This procedure recognizes the analyst’s uncertainty over the nature of the regressors but not the dependent variable. When the analyst is uncertain whether $y_{t}$ is a stationary or unit root process, the test statistics proposed by PSS are uninformative for inference on the existence of a long run relationship (LRR) between $y_{t}$ and $\boldsymbol{x}_{t}$. We propose the long run multiplier (LRM) test statistic as a means of testing for LRRs without knowing whether the series are stationary or unit roots. Using stochastic simulations, we demonstrate the behavior of the test statistic given uncertainty about the univariate dynamics of both $y_{t}$ and $\boldsymbol{x}_{t}$, illustrate the bounds of the test statistic, and generate small sample and approximate asymptotic critical values for the upper and lower bounds for a range of sample sizes and model specifications. We demonstrate the utility of the bounds framework for testing for LRRs in models of public policy mood and presidential success.

Detecting Nonlinear Associations, Plus Comments on Testing Hypotheses About the Correlation Coefficient

2001 ◽  
Vol 26 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Rand R. Wilcox
Keyword(s):  
T Test ◽  
Test Statistic ◽  
The Social ◽  
Zero Correlation ◽  
Common Strategy ◽  
Kolmogorov Smirnov ◽  
Nonlinear Associations ◽  
Student’S T ◽  
Von Mises ◽  
Student’S T Test

Let (Yi,Xi ), i = 1, . . . , n, be a random sample from some p + 1 variate distribution where Xi is a vector of length p. In the social sciences, the most common strategy for detecting an association between Y and the marginal distributions is to test the hypothesis that the corresponding correlations are zero using a standard Student’s t test. There are two practical problems with this strategy. First, for reasons described in the article, there are situations where the correlation between two random variables is zero, but Student’s t test is not even asymptotically correct. In fact, the probability of rejecting can approach one as the sample size gets large, even though the hypothesis of a zero correlation is true. Of course, one can also apply standard methods based on a linear regression model and the least squares estimator, but the same practical problems arise. Second, Student’s t test can miss nonlinear associations. This latter problem is the main motivation for this article. Results of a former study suggest an approach that avoids both of the difficulties just described. Based on simulations, it is found that the Cramér-von Mises form of the test statistic is generally better than the Kolmogorov-Smirnov form. Situations arise where this method has less power than Student’s t test, but this is due in part to t test’s use of an incorrect estimate of the standard error.

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