Efficiency of test for independence after Box–Cox transformation

Freeman, Jade; Modarres, Reza

doi:10.1016/j.jmva.2004.08.005

Cited by 8 publications

(3 citation statements)

References 21 publications

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“…SpDs of plot characteristics showing significant dependence on adult or nymphal SpD every year were selected for multiple regression modelling through the progressive stepwise procedure (XLSTAT 4.2 software; Addinsoft, New York, New York). Because this procedure requires normally distributed data, quantitative variables (including E. vitis SpDs) were transformed using the Box–Cox method (Freeman & Modarres, 2005) and centered‐reduced. The categorical variables (EDGE and VAR) were introduced in the regression as a dummy variable.…”

Section: Methodsmentioning

confidence: 99%

Influence of plot characteristics and surrounding vegetation on the intra‐plot spatial distribution of Empoasca vitis

Decante¹,

Leeuwen²,

Helden³

2009

Agri and Forest Entomology

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1 Spatial distributions of adults and nymphs of Empoasca vitis were assessed during 3 years inside two adjacent vine plots having considerable intra-plot variability, diversified natural ground cover and surrounding vegetation, and no insecticide application. 2 Geostatistical analysis confirmed that, in spite of repeated adult migrations, spatial distributions of summer populations were highly aggregated, similar every year and similar between adults and nymphs. Comparison of insect distribution with intraplot characteristics, such as vine plant vigour (leaf density and leaf chlorophyll concentration) and phenology, plot topography and surrounding vegetation, revealed that E. vitis clearly aggregates in areas with the most vigorous vine plants. 3 Even though the presence of natural enemies in the surrounding vegetation was confirmed by specific observations, we did not observe significant population decrease at the contiguous plot edges. Natural ground cover, together with the absence of insecticide, might allow the spreading and perennial conservation of E. vitis natural enemies inside the plots. 4 Clear adult aggregations observed along downwind woodlands suggest that this vegetation acts as a barrier and intercepts the adults flying passively across the plot. However, this surrounding vegetation could also serve as an alternative refuge when vine water deficit and vine foliage temperature increase.

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Section: Methodsmentioning

confidence: 99%

Influence of plot characteristics and surrounding vegetation on the intra‐plot spatial distribution of Empoasca vitis

Decante¹,

Leeuwen²,

Helden³

2009

Agri and Forest Entomology

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“…, which in turn allows us to test different hypotheses about the correlation-see details in papers by Fisher (1915Fisher ( , 1921, Hotelling (1953), Freeman and Modarres (2005) and a book by Härdle and Simar (2003). In our applications we test the null hypothesis of ρ XY = 0 versus the alternative hypothesis of ρ XY = 0.…”

Section: The Rank Based Quotient Correlationmentioning

confidence: 99%

Quotient correlation: A sample based alternative to Pearson’s correlation

Zhang¹

2008

Ann. Statist.

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The quotient correlation is defined here as an alternative to Pearson's correlation that is more intuitive and flexible in cases where the tail behavior of data is important. It measures nonlinear dependence where the regular correlation coefficient is generally not applicable. One of its most useful features is a test statistic that has high power when testing nonlinear dependence in cases where the Fisher's Ztransformation test may fail to reach a right conclusion. Unlike most asymptotic test statistics, which are either normal or χ 2 , this test statistic has a limiting gamma distribution (henceforth, the gamma test statistic). More than the common usages of correlation, the quotient correlation can easily and intuitively be adjusted to values at tails. This adjustment generates two new concepts-the tail quotient correlation and the tail independence test statistics, which are also gamma statistics. Due to the fact that there is no analogue of the correlation coefficient in extreme value theory, and there does not exist an efficient tail independence test statistic, these two new concepts may open up a new field of study. In addition, an alternative to Spearman's rank correlation, a rank based quotient correlation, is also defined. The advantages of using these new concepts are illustrated with simulated data and a real data analysis of internet traffic.

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“…There is a need for a more recent survey of the field. More recently, Freeman and Modarres (2005) investigated the efficiency and the Downloaded by [Stony Brook University] at 22:20 18 October 2014 power of the normal theory test for independence after a Box-Cox transformation and showed that it is always more efficient to conduct the test of independence after transformation to normality. Teugels and Vanroelen (2004) studied the Box-Cox transformations for heavy-tailed distributions.…”

Section: Introductionmentioning

confidence: 99%

Efficiency of t-Test and Hotelling's T ²-Test After Box-Cox Transformation

Freeman

Modarres

2006

Communications in Statistics - Theory and Methods

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Early investigations of the effects of non-normality indicated that skewness has a greater effect on the distribution of t-statistic than does kurtosis. When the distribution is skewed, the actual p-values can be larger than the values calculated from the t-tables. Transformation of data to normality has shown good results in the case of univariate t-test. In order to reduce the effect of skewness of the distribution on normal-based t-test, one can transform the data and perform the t-test on the transformed scale. This method is not only a remedy for satisfying the distributional assumption, but it also turns out that one can achieve greater efficiency of the test. We investigate the efficiency of tests after a Box-Cox transformation. In particular, we consider the one sample test of location and study the gains in efficiency for onesample t-test following a Box-Cox transformation. Under some conditions, we prove that the asymptotic relative efficiency of transformed t-test and Hotelling's T 2 -test of multivariate location with respect to the same statistic based on untransformed data is at least one.

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Efficiency of test for independence after Box–Cox transformation

Cited by 8 publications

References 21 publications

Influence of plot characteristics and surrounding vegetation on the intra‐plot spatial distribution of Empoasca vitis

Influence of plot characteristics and surrounding vegetation on the intra‐plot spatial distribution of Empoasca vitis

Quotient correlation: A sample based alternative to Pearson’s correlation

Efficiency of t-Test and Hotelling's T ²-Test After Box-Cox Transformation

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Efficiency of test for independence after Box–Cox transformation

Cited by 8 publications

References 21 publications

Influence of plot characteristics and surrounding vegetation on the intra‐plot spatial distribution of Empoasca vitis

Influence of plot characteristics and surrounding vegetation on the intra‐plot spatial distribution of Empoasca vitis

Quotient correlation: A sample based alternative to Pearson’s correlation

Efficiency of t-Test and Hotelling's T 2-Test After Box-Cox Transformation

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Efficiency of t-Test and Hotelling's T ²-Test After Box-Cox Transformation