Statistical Significance Testing with Mahalanobis Distance for Thresholds Estimated from Constant Stimuli Method

2011 ◽  
Vol 24 (2) ◽  
pp. 91-124 ◽  
Author(s):  
Keiji Uchikawa ◽  
Takahiro Hoshino ◽  
Takehiro Nagai
Keyword(s):  
Analysis Of Variance ◽  
Type I Error ◽  
Statistical Significance ◽  
Statistical Testing ◽  
Significance Testing ◽  
Type I ◽  
Testing Methods ◽  
Statistical Significance Testing ◽  
Staircase Method ◽  
Statistical Testing Method

AbstractThe t-test and the analysis of variance are commonly used as statistical significance testing methods. However, they cannot assess the significance of differences between thresholds within individual observers estimated from the constant stimuli method; these thresholds are not defined as averages of samples, but they are rather defined as functions of parameters of psychometric functions fitted to participants' responses. Moreover, the statistics necessary for these statistical testing methods cannot be derived. In this paper, we propose a new statistical testing method to assess the statistical significance of differences between thresholds estimated from the constant stimuli method. The new method can assess not only threshold differences but also main effects and interactions in multifactor experiments, exploiting the asymptotic normality of maximum likelihood estimators and the characteristics of multivariate normal distributions. This proposed method could be used in similar cases to the analysis of variance for thresholds estimated from the adjustment method and the staircase method. Finally, we present some data on simulations in which we tested assumptions, power and type I error of the proposed method.

scholarly journals EXPRESS: Efficacy and Safety of Tadalafil in a Pediatric Population with Pulmonary Arterial Hypertension: Phase 3 randomized, Double Blind Placebo-Controlled Study

2021 ◽  
pp. 204589402110249
Author(s):  
David D Ivy ◽  
Damien Bonnet ◽  
Rolf MF Berger ◽  
Gisela Meyer ◽  
Simin Baygani ◽  
...  
Keyword(s):  
Pediatric Patients ◽  
Statistical Significance ◽  
Significance Testing ◽  
Efficacy And Safety ◽  
Phase 3 ◽  
Statistical Significance Testing ◽  
Double Blind ◽  
Double Blind Placebo ◽  
Treatment Groups ◽  
Pulmonary Arterial

Objective: This study evaluated the efficacy and safety of tadalafil in pediatric patients with pulmonary arterial hypertension (PAH). Methods: This phase-3, international, randomized, multicenter (24 weeks double-blind placebo controlled period; 2-year, open-labelled extension period), add-on (patient’s current endothelin receptor antagonist therapy) study included pediatric patients aged <18 years with PAH. Patients received tadalafil 20 mg or 40 mg based on their weight (Heavy-weight: ≥40 kg; Middle-weight: ≥25—<40 kg) or placebo orally QD for 24 weeks. Primary endpoint was change from baseline in 6-minute walk (6MW) distance in patients aged ≥6 years at Week 24. Sample size was amended from 134 to ≥34 patients, due to serious recruitment challenges. Therefore, statistical significance testing was not performed between treatment groups. Results: Patient demographics and baseline characteristics (N=35; tadalafil=17; placebo=18) were comparable between treatment groups; median age was 14.2 years (6.2 to 17.9 years) and majority (71.4%, n=25) of patients were in HW cohort. Least square mean (SE) changes from baseline in 6MW distance at Week 24 was numerically greater with tadalafil versus placebo (60.48 [20.41] vs 36.60 [20.78] meters; placebo-adjusted mean difference [SD] 23.88 [29.11]). Safety of tadalafil treatment was as expected without any new safety concerns. During study period 1, two patients (1 in each group) discontinued due to investigator’s reported clinical worsening, and no deaths were reported. Conclusions: The statistical significance testing was not performed between the treatment groups due to low sample size, however, the study results show positive trend in improvement in non invasive measurements, commonly utilized by clinicians to evaluate the disease status for children with PAH. Safety of tadalafil treatment was as expected without any new safety signals.

scholarly journals Linkage Disequilibrium in Domestic Sheep

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 1113-1122
Author(s):  
A F McRae ◽  
J C McEwan ◽  
K G Dodds ◽  
T Wilson ◽  
A M Crawford ◽  
...  
Keyword(s):  
Linkage Disequilibrium ◽  
Type I Error ◽  
Statistical Significance ◽  
Domestic Sheep ◽  
Type I ◽  
Single Nucleotide ◽  
Microsatellite Genotype ◽  
Marker Distance ◽  
The Relationship ◽  
Two Populations

Abstract The last decade has seen a dramatic increase in the number of livestock QTL mapping studies. The next challenge awaiting livestock geneticists is to determine the actual genes responsible for variation of economically important traits. With the advent of high density single nucleotide polymorphism (SNP) maps, it may be possible to fine map genes by exploiting linkage disequilibrium between genes of interest and adjacent markers. However, the extent of linkage disequilibrium (LD) is generally unknown for livestock populations. In this article microsatellite genotype data are used to assess the extent of LD in two populations of domestic sheep. High levels of LD were found to extend for tens of centimorgans and declined as a function of marker distance. However, LD was also frequently observed between unlinked markers. The prospects for LD mapping in livestock appear encouraging provided that type I error can be minimized. Properties of the multiallelic LD coefficient D′ were also explored. D′ was found to be significantly related to marker heterozygosity, although the relationship did not appear to unduly influence the overall conclusions. Of potentially greater concern was the observation that D′ may be skewed when rare alleles are present. It is recommended that the statistical significance of LD is used in conjunction with coefficients such as D′ to determine the true extent of LD.

scholarly journals Damaging Real Lives through Obstinacy: Re-Emphasising Why Significance Testing is Wrong

2016 ◽  
Vol 21 (1) ◽  
pp. 102-115 ◽  
Author(s):  
Stephen Gorard
Keyword(s):  
Statistical Significance ◽  
Poor Quality ◽  
Significance Testing ◽  
Significance Tests ◽  
Statistical Significance Testing ◽  
Wrong Answer ◽  
Repeated Calls ◽  
Numeric Data ◽  
Quality Of Research

This paper reminds readers of the absurdity of statistical significance testing, despite its continued widespread use as a supposed method for analysing numeric data. There have been complaints about the poor quality of research employing significance tests for a hundred years, and repeated calls for researchers to stop using and reporting them. There have even been attempted bans. Many thousands of papers have now been written, in all areas of research, explaining why significance tests do not work. There are too many for all to be cited here. This paper summarises the logical problems as described in over 100 of these prior pieces. It then presents a series of demonstrations showing that significance tests do not work in practice. In fact, they are more likely to produce the wrong answer than a right one. The confused use of significance testing has practical and damaging consequences for people's lives. Ending the use of significance tests is a pressing ethical issue for research. Anyone knowing the problems, as described over one hundred years, who continues to teach, use or publish significance tests is acting unethically, and knowingly risking the damage that ensues.

scholarly journals The Other Half of the Story: Effect Size Analysis in Quantitative Research

2013 ◽  
Vol 12 (3) ◽  
pp. 345-351 ◽  
Author(s):  
Jessica Middlemis Maher ◽  
Jonathan C. Markey ◽  
Diane Ebert-May
Keyword(s):  
Educational Research ◽  
Effect Size ◽  
Quantitative Research ◽  
Statistical Significance ◽  
The Other ◽  
Practical Significance ◽  
Significance Testing ◽  
Size Analysis ◽  
Significance Tests ◽  
Statistical Significance Testing

Statistical significance testing is the cornerstone of quantitative research, but studies that fail to report measures of effect size are potentially missing a robust part of the analysis. We provide a rationale for why effect size measures should be included in quantitative discipline-based education research. Examples from both biological and educational research demonstrate the utility of effect size for evaluating practical significance. We also provide details about some effect size indices that are paired with common statistical significance tests used in educational research and offer general suggestions for interpreting effect size measures. Finally, we discuss some inherent limitations of effect size measures and provide further recommendations about reporting confidence intervals.

scholarly journals Implementation of the Omega (ω) Index to detect large-scale systematic cheating

2019 ◽  
Author(s):  
Alvin Vista
Keyword(s):  
Standardized Testing ◽  
Large Scale ◽  
Type I Error ◽  
R Package ◽  
Statistical Testing ◽  
System Level ◽  
Control Group ◽  
Type I ◽  
Data Contamination ◽  
Cheating Detection

Cheating detection is an important issue in standardized testing, especially in large-scale settings. Statistical approaches are often computationally intensive and require specialised software to conduct. We present a two-stage approach that quickly filters suspected groups using statistical testing on an IRT-based answer-copying index. We also present an approach to mitigate data contamination and improve the performance of the index. The computation of the index was implemented through a modified version of an open source R package, thus enabling wider access to the method. Using data from PIRLS 2011 (N=64,232) we conduct a simulation to demonstrate our approach. Type I error was well-controlled and no control group was falsely flagged for cheating, while 16 (combined n=12,569) of the 18 (combined n=14,149) simulated groups were detected. Implications for system-level cheating detection and further improvements of the approach were discussed.

Sign in / Sign up

Export Citation Format

Share Document