Power analyses when comparing trimmed means

Wilcox, Rand R.; Keselman, H. J.

doi:10.22237/jmasm/1020254820

Cited by 10 publications

(3 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3. Extreme values (between -400 and -100, between 100 and 400, under -3500, over 3500) were set to a fixed value (-400, 400, -3500, 3500), which means we winsorised the sample (Wilcox & Keselman, 2002). 4.…”

Section: Association Strengthmentioning

confidence: 99%

Effects of Different Website Designs on First Impressions, Aesthetic Judgements and Memory Performance after Short Presentation

Douneva

Jaron²,

Thielsch

2015

Interact. Comput.

View full text Add to dashboard Cite

The current study investigates how different types of company website designs influence first impressions, aesthetic evaluations, and memory performance. We implemented an online study with a between-subjects design to examine differences between three design categories identified by ten experts in a pretest: SCOFA (strong colours of one colour family), LAPIC (large pictures), and SAPAT (same amount of pictures and text). The data of 458 participants (52.2% female) reveal that a) after an exposure time of five seconds, response times for website-related attributes differ between the categories, b) LAPIC and SAPAT are perceived as more aesthetic than SCOFA, c) memory performance is best on SAPAT sites. These results underline the importance of first impressions of a site's appearance and provide practical guidance for web designers by showing what users associate with certain designs, which designs they prefer, and which sites are the most memorable.

show abstract

Section: Association Strengthmentioning

confidence: 99%

Effects of Different Website Designs on First Impressions, Aesthetic Judgements and Memory Performance after Short Presentation

Douneva

Jaron²,

Thielsch

2015

Interact. Comput.

View full text Add to dashboard Cite

show abstract

“…These "modern methods" consist of some computationally intensive techniques such as the bootstrapped one-step M-estimator (Özdemir, 2013). Other robust methods do not take advantage of modern computation and directly alter the data (Wilcox & Keselman, 2002). For example, Yuen's test for trimmed means consists of removing a predetermined proportion of data from the tail-areas.…”

Section: Introductionmentioning

confidence: 99%

Rethinking Robust Statistics with Modern Bayesian Methods

Williams¹,

Martin²

2017

Preprint

View full text Add to dashboard Cite

Developing robust statistical methods is an important goal for psychological science. Whereas classical methods (i.e., sampling distributions, p-values, etc.) have been thoroughly characterized, Bayesian robust methods remain relatively uncommon in practice and methodological literatures. Here we propose a robust Bayesian model (BHS t ) that accommodates heterogeneous (H) variances by predicting the scale parameter on the log scale and tail-heaviness with a Student-t likelihood (S t). Through simulations with normative and contaminated (i.e., heavy-tailed) data, we demonstrate that BHS t has consistent frequentist properties in terms of type I error, power, and mean squared error compared to three classical robust methods. With a motivating example, we illustrate Bayesian inferential methods such as approximate leave-one-out cross-validation and posterior predictive checks. We end by suggesting areas of improvement for BHS t and discussing Bayesian robust methods in practice.

show abstract

“…Because of this, the Type I error rates is increased and the power of the test starts to reduce. As discussed by Wilcox and Keselman (2002) the standard error of the mean can be seriously affected when the distribution of the data is heavy tailed. As a result, the standard error of the ANOVA becomes bigger than it supposed to, and the power of the test is decreased.…”

Section: Introductionmentioning

confidence: 99%

The Modification and Evaluation of the Alexander-Govern Test in Terms of Power

Ochuko¹,

Abdullah²,

Zain³

et al. 2015

MAS

View full text Add to dashboard Cite

This study centres on the comparison of independent group tests in terms of power, by using parametric method, such as the Alexander-Govern test. The Alexander-Govern (AG) test uses mean as its central tendency measure. It is a better alternative compared to the Welch test, the James test and the ANOVA, because it produces high power and gives good control of Type I error rates for a normal data under variance heterogeneity. But this test is not robust for a non-normal data. When trimmed mean was applied on the test as its central tendency measure under non-normality, the test was only robust for two group condition, but as the number of groups increased more than two groups, the test was no more robust. As a result, a highly robust estimator known as the MOM estimator was applied on the test, as its central tendency measure. This test is not affected by the number of groups, but could not control Type I error rates under skewed heavy tailed distribution. In this study, the Winsorized MOM estimator was applied in the AG test, as its central tendency measure. A simulation of 5,000 data sets were generated and analysed on the test, using the SAS package. The result of the analysis, shows that with the pairing of unbalanced sample size of (15:15:20:30) with equal variance of (1:1:1:1) and the pairing of unbalanced sample size of (15:15:20:30) with unequal variance of (1:1:1:36) with effect size index (f = 0.8), the AGWMOM test only produced a high power value of 0.9562 and 0.8336 compared to the AG test, the AGMOM test and the ANOVA respectively and the test is considered to be sufficient.

show abstract

Power analyses when comparing trimmed means

Cited by 10 publications

References 19 publications

Effects of Different Website Designs on First Impressions, Aesthetic Judgements and Memory Performance after Short Presentation

Effects of Different Website Designs on First Impressions, Aesthetic Judgements and Memory Performance after Short Presentation

Rethinking Robust Statistics with Modern Bayesian Methods

The Modification and Evaluation of the Alexander-Govern Test in Terms of Power

Contact Info

Product

Resources

About