Methodology and Application of the Kruskal-Wallis Test

2014 ◽  
Vol 611 ◽  
pp. 115-120 ◽  
Author(s):  
Eva Ostertagová ◽  
Oskar Ostertag ◽  
Jozef Kováč

This paper describes the methodology and application of the very popular nonparametric test which is a rank based test named as Kruskal-Wallis. This test is useful as a general nonparametric test for comparing more than two independent samples. It can be used to test whether such samples come from the same distribution. This test is powerful alternative to the one-way analysis of variance. Nonparametric ANOVA has no assumption of normality of random error but the independence of random error is required. If the Kruskal-Wallis statistic is significant, the nonparametric multiple comparison tests are useful methods for further analysis. The statistical analysis of the application data in this paper was performed with software MATLAB.

2003 ◽  
Vol 14 (3) ◽  
pp. 197-202 ◽  
Author(s):  
Heloisa Módena Ferreira da Costa ◽  
Renata Cristina Silveira Rodrigues ◽  
Maria da Glória Chiarello de Mattos ◽  
Ricardo Faria Ribeiro

Several formulations of alternative alloys have been proposed for the substitution of gold-based alloys used in Dentistry. Recently, a Ni-Cr-Ti-based alloy has been introduced. The purpose of this work was to verify the marginal adaptation obtained with one-piece superstructures for implant-supported prostheses obtained in Ni-Cr-Ti alloy, compared to a semi-noble alloy Pd-Ag. Eight superstructures for each alloy were produced over 4 implants in the anterior region of the mandible. The superstructures were placed in a torquemeter and the fixation screw of implant #1 was tightened with a 20 Ncm load with the others loosened (Sheffield test). The unfitness (in mm) was measured using a three-dimensional optical measurer in each implant, in the buccal and lingual aspects. The obtained data were submitted to statistical analysis by the analysis of variance and Tukey's test at 5% level. Significant differences were found for the factors material (p<0.05), with Ni-Cr-Ti pieces better than Pd-Ag ones, and implants (p<0.01). There were no significant differences for the factor position and interactions among factors (p>0.05). Based on the analysis of the data, it is possible to conclude that the Ni-Cr-Ti alloy makes possible the obtainment of one-piece implant-supported superstructures with a smaller misfit compared to the one obtained in Pd-Ag alloy, traditionally indicated for this situation. Additional tests may verify the superiority of the Ni-Cr-Ti alloy.


2019 ◽  
Vol 21 (2) ◽  
pp. 53-62
Author(s):  
Ayşe Atay DDS, PhD ◽  
Zülal Palazli DDS ◽  
Işıl Gürdal DDS ◽  
Aslıhan Üşümez DDS, PhD

The purpose of this study is to evaluate the effect of thermocycling on the color change of the amine-free dual-cure resin cements. IPS e.max CAD blocs were cut into specimens of 1 mm thickness (N=28) and cemented with one of the 4 different amine-free dual-cure resin cements (NX3 Nexus [NX], Kerr Dental; Variolink Esthetic DC [VE], Ivoclar Vivadent; Panavia V5 [PV], Kuraray Dental; G-CEM Linkforce [GC], GC Corporation) (n=7). A spectrophotometer was used for color measurements. Specimens were subjected to thermocycling (5°C and 55°C; 5000 and 10000 cycles). Normality of data distribution was tested by using the Kolmogorov-Smirnov test. Statistical analysis was performed using a two-way analysis of variance (ANOVA) and Tukey’s multiple comparison tests at a significance level of p<0.05. ∆E values were significantly influenced by the resin cements and the cycle periods (p<0.05). There were no significant differences between NX and VE groups after 5000 thermocycling, however after 10000 thermocycling VE group showed higher ∆E1 values than NX group (p>0.05).  There were no statistically significant differences between the ∆E0 and ∆E1 values of the GC group, however the other groups were affected after 10000 thermocycling (p>0.05). Amine-free resin cements used for cementation showed color change after thermocycling except GC group. All resin cements were showed clinically acceptable color change after thermocycling (∆E < 3.5).


1992 ◽  
Vol 75 (3_suppl) ◽  
pp. 1124-1126
Author(s):  
John F. Walsh

A statistical test is developed based on the comparison of sums of squared errors associated with two competing models. A model based on cell means is compared to a representation that specifies the means for the treatment conditions. Comparing models is more general than the traditional H0 in analysis of variance wherein all the cell means are assumed equal. The test statistic, Proportional Increase in Error, is computed using the SAS statistical system.


2017 ◽  
Vol 18 (4) ◽  
Author(s):  
Krystyna Chromik ◽  
Anna Burdukiewicz ◽  
Jadwiga Pietraszewska ◽  
Aleksandra Stachoń ◽  
Paweł Wolański ◽  
...  

AbstractPurpose. The aim of the study was to determine differences in anteroposterior spine curvatures between futsal players, soccer players, and non-training students. The results may contribute to the development of present-day knowledge of posturometry, and its implementation in training can help reduce the risk of body posture disorders in athletes. Methods. The examined group consisted of 48 athletes and 38 non-training college students. Body posture parameters were measured with the use of Posturometr-S. The normality of distribution was checked with the Shapiro-Wilk test, and the differences between the groups were measured with ANOVA and the Bonferroni post-hoc test. The level of statistical significance was set at p < 0.05. Results. The analysis of angle values revealed the widest and most similar measurements in the group of futsal players and soccer players. The analysis of variance proved statistically significant differences between the soccer players and futsal players (p = 0.003). The difference between the soccer players and non-training students was statistically significant. The highest γ angular value was measured in non-training students, followed by futsal players and soccer players. The statistical analysis revealed significant differences between the non-training students and futsal players, as well as non-training students and soccer players (p < 0.001). Conclusions. A complex assessment of athletes’ body posture is crucial in injury prevention. Training overloads may often lead to disorders of the organ of locomotion and affect the correct body posture in athletes. This, in turn, may result in pains and injuries.


2021 ◽  
Vol 1 (2) ◽  
pp. 053-067
Author(s):  
Apezi Okiemute EDEWOR ◽  
Augustus Orowhigo ATUBI

The derived savanna landscape of Delta state situated within the rainforest region are always considered with apathy as they are viewed as idle, marginalized or abandoned landscapes. The study therefore focused on statistical analysis of the physiochemical properties of the derived savanna, rainforest and fallow landscapes of Delta state. The statistical analysis gave impetus for the derivation of Soil Fertility Index (SFI). The hypothesis formulated to guide the study was tested using the one-way Analysis of Variance (ANOVA). This was used to test the variation between soil physiochemical parameters of the various landscapes at 0.05 significance level. Specifically, the study found out that the physiochemical parameters of the landscapes studied are significantly correlated. Thus, implying basic similarities in soil fertility and soil constituent tendencies between the landscapes.


Author(s):  
Fathima Banu Raza ◽  
Anand Kumar

The o-rings in ball retained overdentures deteriorate with time and need replacement to restore the retentive quality. We evaluated retrospectively the mechanical properties of o-rings after 3 years in function in one and two-piece implant-supported overdentures. The o-rings were retrieved from one-piece (Myriad snap, Equinox-Straumann, 3.3 x 13mm) and two-piece (Neo Biotech, 3.3 x 13mm) implant-supported overdenture patients. A total of 16 pairs of matrices were tested for wear, type of damage and elasticity using Pin on Disc method, USB Digital Camera in 30x zoom and Universal Tensile Machine respectively. The statistical analysis for independent groups were done with the Mann-Whitney U test. Assessment of used O-rings showed 84% more wear in the two-piece system with an abrasive type of damage while 46% wear in the one-piece system with a compressive type of damage. The o-rings in one-piece system showed increase in elongation and maximum displacement to 2% and 7% respectively, while two-piece system showed decrease in elongation and maximum displacement by 13% and 6% respectively. In one-piece system, the loss of retention was more with slow wear rate and in two-piece system, the wear resistance of O-rings decreased due to increased stiffness. Further studies to evaluate the changes in O-ring with increased sample size and at interval 1 year will pave way for insight into the progressive changes in the mechanical properties of an O-ring.


2018 ◽  
Vol 41 (4) ◽  
pp. 348-368 ◽  
Author(s):  
Sivanes Phillipson ◽  
Shane N. Phillipson ◽  
Sarika Kewalramani

This article explored the variability of parental educational mind-sets among Australian parents toward the accessible educational and learning capitals that may affect their children’s educational achievement. The participants ( N = 1,917) responded to the Family Educational and Learning Capitals Questionnaire as well as their ethnic identity. Parents also reported their children’s numeracy scores in a standardized test of achievement. Six major groups were adequate for statistical analysis, including Australians, British, Chinese, Indian, Other Asian, and Other European. A multiple comparison analysis was performed on the responses by parents from the six ethnic groups to examine the differences in parent responses to access to capitals. Controlled for ethnic groups, stepwise regression analysis showed which capitals predicted numeracy achievement of their children. The results indicated that within this sample of Australian parents, there is variability across different ethnic groups in what is considered important in their children’s educational achievement and this variability is associated with differences in numeracy outcomes.


10.17158/514 ◽  
2016 ◽  
Vol 19 (2) ◽  
Author(s):  
Jovelyn M. Durango ◽  
Carlito P. Yurango

<p>The advent of technology has improved the way statistics is taught and learned. It is claimed that the use of computer-based instructional tools can actively explore the meaning of statistical concepts among the students, as well as enhance their learning experiences. This study aimed to compare three methods of statistical analysis namely, the traditional technique (use of the calculator), Microsoft Excel and Statistical Package for Social Sciences (SPSS) software. This investigation utilized the experimental design, specifically the One-Group Pretest – Posttest Design. There were six education students who self-assessed their attitude before and after the introduction of the use of various computation techniques and performed the statistical analysis considering also the completion time required for each process. Results of the study revealed an increase in the level of attitude among the respondents form the pretest to the posttest. Also, the cognitive level regardless of the approach was very high. However, the t-test failed to establish a significant difference in the attitude among the respondents. On the other hand, there were significant differences in both the test scores and completion time of the respondents in the three methods in favor of SPSS.</p><p> </p><p><strong>Keywords: </strong>Information technology, statistics, traditional technique, Microsoft excel, SPSS, comparative analysis, experimental research design, Davao City, Philippines. </p>


2002 ◽  
pp. 59-66
Author(s):  
Vojislav Bajic ◽  
Milorad Danilovic

Based on the elements of statistical analysis on the dependence of fuel and lubricant consumption on tree diameter, it was assessed that with the increase of tree diameter, the fuel and lubricant consumption in the young oak and hornbeam stands decreases significantly, both in clear felling and in thinning and that the function form Y=exp(a+b x X?1) is the best description of the correlation The consumption of fuel compared to lubricant consumption is almost double, which agrees with the results of the previous studies. Average consumption of fuel and lubricant is 17.43 mL x tree?1, on the plots 20.27 mL x tree?1, average consumption of lubricant per tree on skid roads is 9.4 mL x tree?1, on the plots 11 mL x tree?1. The higher consumption of fuel and lubricant on the plots with selective thinning is the consequence of the longer time needed for the conversion per tree, compared to that in clear felling The consumption of fuel per unit area on the skid roads (clear felling) is 22.9 L x ha?1, on the plots (selective thinning) 7.6 L x ha?1. The consumption of lubricant on the skid roads is 13.3 L x ha?1, on the plots 4.29 L x ha?1. The higher consumption of fuel and lubricant per unit area on the skid roads is due to the difference in the number of trees per unit area Based on the results of the analysis of variance, it was found out that between fuel and lubricant consumption in selective thinning and in felling the trees along tractor skid roads there is no statistically significant difference at the level of significance of 95%. So, for practical purposes, the unique norms of consumption can be established for the stands similar to those in which the study was performed.


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