Hi, I'm a new user of R. My background is Electrical Engineering, so please bear with me if this is a silly question.
I'm trying to assess whether the results of an experiment satisfy the hypothesis of homoscedasticity (my ultimate goal is to use ANOVA). The result of the experiment is mean delay (dT), which depends on three factors, topology, drift, and lambda. The first two factors are categorical (with 4 levels each) and the last one is numerical, with two levels. A sample of my data is as follows: dT Topology Drift lambda 258.789 Tree b1 .43 244.195 Tree b1 .43 115.961 Tree b2 .3 115.183 Tree b2 .3 I would like to separate dT in the 32 samples (4x4x2), and test if the variance of each sample is equal to the other 31 samples. I tried using fligner.test and bartlett.test, but either test seems to only work for one factor: > fligner.test( dT ~ Topology + Drift + lambda) Fligner-Killeen test of homogeneity of variances data: dT by Topology by Drift by lambda Fligner-Killeen:med chi-squared = 15.4343, df = 2, p-value = 0.0004451 > fligner.test( dT ~ Topology ) Fligner-Killeen test of homogeneity of variances data: dT by Topology Fligner-Killeen:med chi-squared = 15.4343, df = 2, p-value = 0.0004451 As I see from the previous two outputs, fligner.test only takes into account the first factor. Similar results are obtained for bartlett.test. At this point I don't know if I'm using the test incorrectly or something else. I would really appreciate any help. I'm using R version 2.7.2 (2008-08-25) in Windows XP. Many thanks in advance Javier ---------------------------------------------------- Javier Acuna Electrical Engineering Grad Student Universidad de Chile [EMAIL PROTECTED] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.