Multiple Comparison of Medians Using Permutation Tests

A robust method is proposed for simultaneous pairwise comparison using permutation tests and median differences. The new procedure provides strong control of familywise error rate and has better power properties than the median procedure of Nemenyi/Levy. It can be more powerful than the Tukey-Kramer procedure using mean differences, especially for nonnormal distributions and unequal sample sizes

Performing Two-Way Analysis of Variance Under Variance Heterogeneity

Small sample properties of the method proposed by Brunner et al. (1997) for performing two-way analysis of variance are compared to those of the normal based ANOVA method for factorial arrangements. Different effect sizes, sample sizes, and error structures are utilized in a simulation study to compare type I error rates and power of the two methods. An SAS program is also presented to assist those wishing to implement the Brunner method to real data

JMASM8: Using SAS To Perform Two-Way Analysis Of Variance Under Variance Heterogeneity

We present SAS code to implement the method proposed by Brunner et al. (1997) for performing two-way analysis of variance under variance heterogeneity

USING RANKS TO PERFORM EXACT AND ESTIMATED EXACT TESTS IN DESIGNED EXPERIMENTS

A procedure is studied that uses rank transformed data to perform exact and estimated exact tests which is an alternative to the commonly used F-ratio test procedure. First, a common parametric test statistic is computed using rank transformed data, where two methods of ranking - ranks taken of the original observations, and ranks taken after aligning the observations - are studied. Significance is then determined using either the exact permutation distribution of the statistic or an estimate of this distribution based on a random sample of all possible permutations. Simulation studies compare the performance of this method to both the normal theory parametric F-test and the traditional rank transform procedure. Power and nominal type-I error rates are compared under conditions when normal theory assumptions are satisfied as well as when these assumptions are violated. The method is studied for a two factor factorial arrangement of treatments in a completely randomized design and also for a split-unit experiment

The Grizzly, November 30, 1984

Board Approves $825 Increase in Annual Tuition, Room and Board • Glick Summons Students: Wood Responds to Roving Reporter • Shorts: Messiah; Spring Jobs; Ice Fishing • Hoop Team Upsets West Chester in Opener • Booters Finish Great Season • Mers and Vers Attend Bloomsburg Invitational • Whatley Plans to Expand Intramurals • Co-ed Volleyball Ends • Fencing in First Competition • Scenes From the Soccer Seasonhttps://digitalcommons.ursinus.edu/grizzlynews/1129/thumbnail.jp

JMASM8: Using SAS To Perform Two-Way Analysis Of Variance Under Variance Heterogeneity

We present SAS code to implement the method proposed by Brunner et al. (1997) for performing two-way analysis of variance under variance heterogeneity

Poor long-term patient and graft survival after primary percutaneous coronary intervention for acute myocardial infarction due to saphenous vein graft occlusion

Primary percutaneous coronary intervention (PCI) for ST segment elevation myocardial infarction (STEMI) due to saphenous vein graft (SVG) occlusion has been associated with poor procedural results and poor short-term outcomes, but long-term graft patency and patient survival have not been evaluated. Consecutive patients (n = 2,240) with STEMI treated with primary PCI from 1984 to 2003 were followed for 6.6 years (median). Follow-up angiography was obtained in 80% of hospital survivors following primary PCI for SVG occlusion at 2.3 years (median). Patients with primary PCI for SVG occlusion (n = 57) vs. native artery occlusion had more prior MI, advanced Killip class, and three-vessel coronary disease and lower acute ejection fraction (EF). Patients with SVG occlusion had lower rates of TIMI 3 flow post-PCI (80.7% vs. 93.6%; P = 0.0001), higher in-hospital mortality (21.1% vs. 8.0%; P = 0.0004), and lower follow-up EF (49.3% vs. 54.7%; P = 0.055). Culprit SVGs were patent in 64% of patients at 1 year and 56% at 5 years. Late survival was strikingly worse in patients with primary PCI for SVG occlusion vs. native vessel occlusion (49% vs. 76% at 10 years), and SVG occlusion was the second strongest predictor of late cardiac mortality by multivariate analysis (HR = 2.11; 95% CI = 1.38–3.23; P = 0.0006). Patients with STEMI due to SVG occlusion treated with primary PCI have poor acute procedural results, frequent late reocclusion, and very high late mortality. The introduction of new adjunctive therapies (distal protection, thrombectomy, and drug-eluting stents) may improve short-term outcomes, but improved long-term outcomes may require new and more durable revascularization strategies

SAS Program To Perform Analysis Of Factorial Experiments Using Aligned Ranks

In situations when analysis of variance procedures are utilized, it is generally thought important that the assumptions associated with analysis of variance be fulfilled. Two assumptions that are often examined in the course of an analysis are normality and homogeneity of variance. To what extent violation of one or both of these assumptions influences inferences made in an analysis of variance is not fully known, but remedial measures to deal with these problems have been often used

Pairwise comparison of scale using deviances

Permutation tests based on medians are examined for pairwise comparison of scale. Tests that have been found in the literature to be effective for comparing scale for two groups are extended to the case of all pairwise comparisons, using the Tukey-type adjustment of Richter and McCann [Multiple comparison of medians using permutation tests. J Mod Appl Stat Methods. 2007;6(2):399–412] to guarantee strong Type I error rate control. Power and Type I error rate estimates are computed using simulated data. A method based on the ratio of deviances performed best and appears to be the best overall test