similar to: Wald tests and Huberized variances (was: A comment about R:)

Hi all, I am a real novice to R. :) I am struggling with a problem for generating colored dendrogram. I have searched the R list and complied/collected a R code which can generated a colored dendrogram based on the rainbow color and 4x4 similarity matrix (say matrix:m). In this dendrogram, each leaf is colored differently. But, I do not want the leaf colored on a random basis. I want to assign

Hi folks: Does anyone know of a way to do (linear) hypothesis tests of parameters after fitting a maximum-likelihood model w/ optim? I can't seem to find anything like a Wald test whose documentation says it applies to optim output. Also, thanks again to everyone who gave me feedback on the robustness of ML estimation in R! Peter ********************************

I have two models, controlled by dummy variables to see if the models can be combined into one model with similar intercepts and slopes. Has anyone tried to conduct this type of test in R. I am utilizing the econometric idea of hypothesis testing through the hypothesis of coincidence. I have tried to run an anova with test of Chisq, but I am not sure what the results are telling. In addition, I

# Your mailer is set to "none" (default on Windows), # hence we cannot send the bug report directly from R. # Please copy the bug report (after finishing it) to # your favorite email program and send it to # # r-bugs@biostat.ku.dk # ###################################################### I stumbled on this error while doing a classroom demonstration. The error is reproducible,

Dear all, I'm trying to run a Wald Test for the Penalized Fixed Effects using the rqpd package. Actually, I'd like to test if the coefficients associated to the same variable are statistically different among the quantiles. The usual wald.test, waldtest or anova.rq don't work for rqpd. I would appreciate any help. Thank you. Regards, Fernando Parmagnani, M.A., Economics University

I have a doubt about the calculation of tests for fixed effects in mixed-effects models. I have read that, except in well-balanced designs, the F statistic that is usually calculated for ANOVA tables may be far from being distributed as an exact F distribution, and that's the reason why the anova method on "mer" objects (calculated by lmer) do not calculate the denominator df nor a

Hi all, It seems that I can get White's (HC3) test using MASS. The syntax I used for the particular problem is anova(scireg3, white.adjust="hc3") where scireg3 is an object from the lm function. But, the anova summary table is all I get. I don't get the new estimates or standard errors correcting for heteroskedasticity. Is there a way to get that information? Thanks

*H*i, I am trying to fit a GEE model with *geeglm* function. The model is the following: Modelo<-geeglm(sqrt ~Tra+ Mes, id=Lugar , data=datos, family=gaussian(identity), corstr="independence") *Tra( is a experimental treatment, 2 levels)*, *Mes* (is the month of take data, 4 levels) and *Lugar* (is the site of study, 3 levels) are categorical variables and *sqrt* (sqrt of Total

Dear R users,    my question concerns my interest in comparing the beta coefficients between two identical regression models in two (actually 3) groups. Disclaimer: I am quite new to R, so I might be missing some terminology that I have not come across.   I am trying to find out if I can easily implement a Wald test in R for this, but the only relevant thing that I came across is this link

Dear R members, I am new in using frailty models in survival analyses and am getting some contrasting results when I compare the Wald and likelihood ratio tests provided by the r output. I am testing the survivorship of different sunflower interspecific crosses using cytoplasm (Cyt), Pollen and the interaction Cyt*Pollen as fixed effects, and sub-block as a random effect. I stratified

Hi I'm having some difficulty understanding my output (below) from GEE. the person who wrote the program included some comments about the '3-th term gives diff between hyp/ox at time..', and after created an L vector to use for a WALD test. I was wondering if someone could help me understand the GEE output, the programmers comment, how L was determined, and its use in the WALD

I'd like to be able to test linear hypotheses after setting up and running a model using optim or perhaps nlm. One hypothesis I need to test are that the average of several coefficients is less than zero, so I don't believe I can use the likelihood ratio test. I can't seem to find a provision anywhere for testing linear combinations of coefficients after max. likelihood. Cheers

Hola a todos y todas, Gracias por vuestro apoyo en cantidad de preguntas anteriores, de nuevo os escribo para compartir una duda: Estoy trabajando con un modelo bien sencillo, es una regresión simple, pero me gustaría comprobar la significación estadística de cada uno de los coeficientes de regresión en el modelo. La idea es hacer un contraste de hipótesis. Me he descargado el paquete

Buenos días, Gracias Carlos, siguiendo el ejemplo que comentas, esto es lo que he introducido en el Scrip de RStudio: *library(xlsx)* *library(xlsxjars)* *library(rJava)* *library(aod)* *R<-read.csv("2002.CSV", sep=";", dec=",", header=T)* *attach(R)* *group<-gl(2,670,1340,labels= c("AVE", "Log.Imports.Value.in.1000.USD"))*

I have a question about the Wald test F-statistics that are calculated when the anova() command is used on a singular gls or lme object. As I recall from my linear models class, the Wald test examines H0: C'B = d0 vs Ha: C'B != d0. Does anybody know how this C matrix is constructed in R? Is there a way to see the C matrix that R is using? In my situation, I'm looking at

Dear R-Helpers, I'm searching for an R package that will produce power analyses for linear Wald tests. I have conducted a thorough analysis and come up with a pile of negative results (I'm the King, baby). I found asypow, which applies to likelihood ratio tests. However, we generally have the power to do Wald tests, I just need to prove it so that we can publish it ;) If this is a

hello, I work since a few time on R and i wanted to know how to obtain the Wald chi square value when you make a binary logistic regression. In fact, i have the z value and the signification but is there a script to see what is the value of Wald chi square. You can see my model below, Best regards, S??verine Erhel [Previously saved workspace restored] > m3 = glm(reponse2 ~ form +

Dear all, I am trying to compare the estimated coefficients of a quantile regression model between two different samples. It is a Wald test, but I cannot find one way to do that in R.The samples are collected conditional on a specific characteristic and I would like to test whether such characteristic indeed affect the estimators. The problem in the test anova.rq is that the response variable

Dear expeRts, there is obviously a general trend to use model comparisons, LRT and AIC instead of Wald-test-based significance, at least in the R community. I personally like this approach. And, when using LME's, it seems to be the preferred way (concluded from postings of Brian Ripley and Douglas Bates' article in R-News 5(2005)1), esp. because of problems with the d.f. approximation.

Stephen, thanks for your effort. The more appropriate list for this discussion is probably R-devel (as far as I understand it) so I've moved the discussion there. Related topics have already been discussed in the past. Specifically, I remember contributions by Paul Johnson ("rockchalk" package) and John Fox ("effects" and "car" package) as their packages