search for: heterogen

My data have heterogeneity of variance (in a categorical variable), do I need to specify a variance structure accounting for this in my model or do GLMMs by their nature account for such heterogeneity (as a result of using deviances rather than variances)? And if I do need to do this, how do I do it (e.g. using something...

Hello, I'm interested in correcting for and measuring unobserved heterogeneity ("missing variables") using R. In particular, I'm searching for a simple way to measure the amount of unobserved heterogeneity remaining in a series of increasingly complex models (adding additional variables to each new model) on the same data. I have a static databas...

Dear all, I try to use read.table to get the data from a tab delimited file, and some of the data is shown below: 3185 heterogeneous nuclear ribonucleoprotein F 3187 heterogeneous nuclear ribonucleoprotein H1 (H) 3188 heterogeneous nuclear ribonucleoprotein H2 (H') 3189 heterogeneous nuclear ribonucleoprotein H3 (2H9) 3190 heterogeneous nuclear ribonucleoprotein K /// heterogeneous nuclear ribonucleoprotein K...

Classification: UNCLASSIFIED Caveats: NONE A similar question has been posted in the past but never answered. My question is this: for probit analysis, how do you program a 95% confidence interval for the LD50 (or LC50, ec50, etc.), including a heterogeneity factor as written about in "Probit Analysis" by Finney(1971)? The heterogeneity factor comes into play through the chi-squared test for homogeneity and is equal to h=chi^2/(k-2), where k is the number of doses and k-2 are the degrees of freedom. I have done a lot of research on this...

...matrices using advice from John Fox (see <http://tolstoy.newcastle.edu.au/R/e5/help/08/12/8773.html> and <http://blog.lib.umn.edu/moor0554/canoemoore/2009/09/sem_complex_samples_r_update.html>). However, since I have categorical/ordinal variables, I would like to compute a weighted heterogeneous correlation matrix with hetcor(). Is there a way to do this in R? I couldn't find any guidance in the r-help archives or in the polycor help files. Should I truncate the sampling weights to integers and then populate the data set with redundant rows/cases so that the number of rows equa...

Dear list members, I am looking for an alternative function for a two-way ANOVA in the case of variance heterogeneity. For one-way ANOVA, I found oneway.test(), but I didn't find anything alike for two-way ANOVA. Does anyone have a suggestion? Thank you! Maike Luhmann Freie Universit?t Berlin

Hi all, I have major heterogeneity in variances across labs (100-fold). There is no apparent variance heterogeneity across y-hat. By using lme4 in the following way, am I accounting for the variance differences in labs?: lmer(y ~ fixed1 + covariates + (fixed1|labs)) I'm not sure that it is - I think it is only allowing the...

..., 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) ftype = c(0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2) factor(amph) factor(ftype) factor(mix) ## Fit ftype... > rma(KL,VL,mods=ftype) Mixed-Effects Model (k = 19; tau^2 estimator: REML) tau^2 (estimate of residual amount of heterogeneity): 0.0111 (SE = 0.0095) tau (sqrt of the estimate of residual heterogeneity): 0.1054 Test for Residual Heterogeneity: QE(df = 17) = 43.0937, p-val = 0.0005 Test of Moderators (coefficient(s) 2): QM(df = 1) = 1.1069, p-val = 0.2928 Model Results: estimate se zval pval...

...is problematic as it makes everything from simple constant propagation to kernel splitting/fusion painfully hard. The proposal is to merge host and device code in a single module during the optimization steps. This should not induce any cost (if people don't use the functionality). But how do heterogeneous modules help? -------------------------------------- Assuming we have heterogeneous LLVM-IR modules we can look at accelerator code optimization as an interprocedural optimization problem. You basically call the "kernel" but you cannot inline it. So you know the call site(s) and argu...

Hello. I want to estimate the predicted values and standard errors of Y=f(t) and its first derivative at each unique value of t using the smooth.spline function. However, the data (plant growth as a function of time) show substantial heterogeneity of variance since the variance of plant mass increases over time. What is the consequence of such heterogeneity of variance in terms of bias in the estimate of the predicted value of Y and its first derivative? I could Ln-transform the data to achieve homogeneity of variance, but this would g...

Dear All My data consists in 96 groups, each one with 10 observations. Levene's test suggests that the variances are not equal, and therefore I have tried to apply the classical transformations to have homocedasticity in order to be able to use ANOVA. Unfortunately, no transformation that I have used transforms my data into data with homocedasticity. The histogram of variances is at

I have heterogeneous variance in a two-way mixed effects ANOVA, with more than 2 groups in each factor. Is there something like oneway.test or a Brown-Forsythe test that will let me test for differences in means? Thanks! -Keith

...replicated goodness-of-fit experiments (observed compared to expected counts in categories) and these replicates are nested within a factor. The expected counts in each cell are external (from a scientific model being tested). The calculations I need within each level of the nesting factor are a heterogeneity G test, with the total G and the pooled G across replicates. Then I would like to form an F ratio equal to the ratio of pooled G divided by its degrees of freedom to heterogeneity G divided by its degrees of freedom. The F ratio would (I think) test the hypothesis that the badness-of-fit in t...

...this a "homogeneous" configuration. Suppose you buy the hardware to build such a pool. Two years go by, and you want to grow the pool. Changes in drive size, hardware, cpu, etc will be such that it won't be possible (or sensible) to buy the same exact hardware, sized drives, etc... A heterogeneous pool is unavoidable. Is there a general case solution for this problem? Is something planned to deal with this problem? I can only think of a few specific corner case solutions. Another problem that comes to mind is ensuring that the older slower servers don't act as bottlenecks to the wh...

...bset of the axes) and the task is (exactly) to separate this clusters among the principal components. I have done my complete work using prcomp() and tested combinations of center=FALSE/TRUE and scale=FALSE/TRUE. I would like to now check this "between-axes" vs "within-axes" heterogeneity of my data and cross-check results with the various tested PCA-versions. Is there any (official or custom) function available in R that could answer this question? Some relative/comparative (preferrable simple and intuitive) measure(s)? Something that would graphically perhaps give an indic...

Christos, We would be very interested in learning more about this. In my group, we (Prakalp Srivastava, Maria Kotsifakou and I) have been working on LLVM extensions to make it easier to target a wide range of accelerators in a heterogeneous mobile device, such as Qualcomm's Snapdragon and other APUs. Our approach has been to (a) add better abstractions of parallelism to the LLVM instruction set that can be mapped down to a wide range of parallel hardware accelerators; and (b) to develop optimizing "back-end" transla...

Dear R-help: Does anyone know of a package in R that will do Welch's modified F-test for heterogeneous error variances? Are there other statistical techniques available in R that test the equality of means when homoscedastisity is violated? 't.test' does this in the pairwise sense when var.equal = TRUE. With best wishes and kind regards I am Sincerely, Corey A. Moffet Support Scienti...

...s [cough]SAS[cough] would be great too.) thanks, Ben Bolker Gaines, Steven D., and William R. Rice. 1990. Analysis of Biological Data When there are Ordered Expectations. The American Naturalist 135, no. 2:310-317. Rice, William R., and Steven D. Gaines. 1994a. Extending Nondirectional Heterogeneity Tests to Evaluate Simply Ordered Alternative Hypotheses. Proceedings of the National Academy of Sciences of the United States of America 91, no. 1:225-226. Rice, William R., and Steven D. Gaines. 1994b. The Ordered-Heterogeneity Family of Tests. Biometrics 50, no. 3:746-752. --------------...

Dear R-users, I am trying to make Snow and Rmpi working on an heterogenous cluster of linux computers. The master computer is built on a 64 bit architecture whereas all nodes are built on a 32 bit architecture. LAM/MPI was installed successfully on all machine. LAM boots correctly on the master computer and it recognizes all nodes defined in the lamhosts file. How...

...Exp(form=~depcptwithextybf),varFixed(form=~FebNAO)) also if you have two variables with the same weights function would you write that as: VFcomb<-varComb(varExp(form=~depcptwithextybf),varExp(form=~FebNAO)) thanks Rebecca -- View this message in context: http://www.nabble.com/Dealing-with-heterogeneity-with-varComb-weights-tp25491971p25491971.html Sent from the R help mailing list archive at Nabble.com.