search for: heteroskedasticity

Hi- I want to fit a model with crossed random effects and heteroskedastic level-1 errors where inferences about fixed effects are of primary interest. The dimension of the random effects is making the model computationally prohibitive using lme() where I could model the heteroskedasticity with the "weights" argument. I am aware that the weights argument to lmer() cannot be used to estimate a heteroskedastic variance function with unknown parameters. However my data situation is such that I am able to assign each unit uniquely to one of four groups and I am willing to tre...

Hello everyone, I'm working on a current linear model Y = a0 + a1* X1 + ... + a7*X7 + residuals. And I know that this model presents both heteroskedasticity (tried Breusch-Pagan test and White test) and residuals autocorrelation (using Durbin Watson test). Ultimately, this model being meant to be used for predictions, I would like to be able to remove this heteroskedasticity and residuals autocorrelation. What I've done until now : - I've use...

Hello there, I have a linear regression model for which I estimated heteroskedasticity-robust (Huber-White) standard errors using the coeftest function in the lmtest-package. Now I would like to inspect the predicted values of the dependent variable for particular groups and include a confidence interval for this prediction. My question: is it possible to estimate confidence interv...

I am trying to compute the white heteroskedasticity-robust standard errors (also called the Huber standard errors) in a linear model, but I can't seem to find a function to do it. I know that the design library in S+ has something like this (robcov?), but I have not yet seen this library ported to R. Anyone know if there is already a function...

Hi, I'm dealing with time series. I usually use stl() to estimate trend, stagionality and residuals. I test for normality of residuals using shapiro.test(), but I can't test for autocorrelation and heteroskedasticity. Is there a way to perform Durbin-Watson test and Breusch-Pagan test (or other simalar tests) for time series? I find dwtest() and bptest() in the package lmtest, but it requieres an lm object, while I've a ts object. Any help will be appreciated. Best Vito ===== Diventare costruttori di soluz...

Hi all, I just discovered R a couple of days ago and I must say it rocks. I've been looking for heteroskedasticity tests and couldn't find any, however. Particularly, I've been told in one of my courses on econometrics of White's method (>< white.test()). The test's statistic is beta / sqrt(W), where W is Var(beta) "? la White", that is the beta(i) matrix is replaced by the resi...

Hello guys! Sorry to bother with such a question I was trying to generate a monte carlo simulation with heteroskedasticity errors. but I am not sure if the command line that I had wrote is quite correct. the type of heteroskedasticity that I want to create is such as var(e) = var(x^4) I began my work with this x<- rnorm (100, 2,0.4) # generating an indepedent random variable e<- rnorm(100,0,x^2) # generating t...

...nly thing is that only the weight is provided. Thus, I constructed my survey design as: svdes<-svydesign(id=~1, weights=~weightvar, data=dataset) Then, I want to run an OLS model, so: fitsurv<-svyglm(y~x1+x2+x3...xk, design=svdes, data=dataset) But, I want to check if there is evidence of heteroskedasticity. If so, how would I correct the standard errors? Can the "sandwich" library do this? Are the standard errors already adjusted. How else can I verify if heteroskedasticity is still present? Can I still use the bptest()? I read an earlier post where someone used a dataset example entitled...

I'm new to R and some what new to the world of stats. I got frustrated with excel and found R. Enough of that already. I'm trying to test and correct for Heteroskedasticity I have data in a csv file that I load and store in a dataframe. > ds <- read.csv("book2.csv") > df <- data.frame(ds) I then preform a OLS regression: > lmfit <- lm(df$y~df$x) To test for Heteroskedasticity, I run the BPtest: > bptest(lmfit) student...

Hi all, Does anyone know how to report heteroskedasticity and autocorrelation-consistent standard errors when using the "spm" command in SemiPar package? Suppose the original command is sp1<-spm(y~x1+x2+f(x3), random=~1,group=id) Any suggestion would be greatly appreciated. Thanks, Susan [[alternative HTML version deleted]]

I just corrected std.error of my 'model'(Multi Regression). Then how can I get new t and p-values? Isn't there any R command which shows new t and p values? -- View this message in context: http://r.789695.n4.nabble.com/After-heteroskedasticity-correction-how-can-I-get-new-confidential-interval-tp3095643p3095643.html Sent from the R help mailing list archive at Nabble.com.

Hey I am trying to run /coeftest()/ using a heteroskedasticity-consistent estimation of the covariance matrix and i get this error: # packages >library(lmtest) >library(sandwich) #test > coeftest(*GSm_inc.pool*, vcov = vcovHC(*GSm_inc.pool*, method="arellano", > type="HC3")) /Fehler in 1 - diaghat : nicht-numerisches Argument...

...ution of my residual ?e?. May be a dump question and somehow ashaming because it?s the concept of CAPM-GARCH =) but I have to admit I don?t get it. Thanks for your time and help Regards Tonio -- View this message in context: http://r.789695.n4.nabble.com/CAPM-GARCH-Regression-analysis-with-heteroskedasticity-tp4105346p4105346.html Sent from the R help mailing list archive at Nabble.com.

Dear all, Trying to test for heteroskedasticity I tried several test from the car package respectively lmtest. Now that they produce rather different results i am somewhat clueless how to deal with it. Here is what I did: 1. I plotted fitted.values vs residuals and somewhat intuitively believe, it isn't really increasing... 2. furt...

Hello, I've had no luck finding an R package that has the ability to estimate a Tobit model allowing for heteroskedasticity (multiplicative, for example). Am I missing something in survReg? Is there another package that I'm unaware of? Is there an add-on package that will test for heteroskedasticity? Thanks for your help. Cheers, Alan Spearot -- Alan Spearot Department of Economics University of Wisconsin - Mad...

Dear All, I would like to introduce the above-named new package that is now available on CRAN: https://cran.r-project.org/web/packages/skedastic/index.html The package features numerous 'classical' heteroskedasticity tests (some not previously available in any published R package) as well as one very new test that appeared in the literature only in 2019. Feedback on bugs/issues is most welcome at https://github.com/tjfarrar/skedastic and reviews are welcome at crantastic: https://crantastic.org/packages/skedas...

Dear All, I would like to introduce the above-named new package that is now available on CRAN: https://cran.r-project.org/web/packages/skedastic/index.html The package features numerous 'classical' heteroskedasticity tests (some not previously available in any published R package) as well as one very new test that appeared in the literature only in 2019. Feedback on bugs/issues is most welcome at https://github.com/tjfarrar/skedastic and reviews are welcome at crantastic: https://crantastic.org/packages/skedas...

Hi all, I'm getting contradictory results from bptest and ncvTest on a model calculated by GLS as: olslm = lm(log(rr)~log(aloi)*reg*inv, data) varlm = lm(I(residuals(olslm)^2)~log(aloi)*reg*inv, data) glslm = lm(log(rr)~log(aloi)*reg*inv, data, weights=1/fitted(varlm)) Testing both olslm and glslm with both ncvTest and bptest gives: > ncvTest(olslm) Non-constant Variance Score Test

R-help Digest wrote: > ------------------------------ > > Date: Thu, 07 Dec 2000 18:28:09 +0100 > From: Uwe Ligges <ligges at statistik.uni-dortmund.de> > Subject: Re: [R] Heteroskedasticity in R > > Vincent Leycuras wrote: > > > > Hi all, > > > > I just discovered R a couple of days ago and I must say it rocks. I've been > > looking for heteroskedasticity tests and couldn't find any, however. > > Particularly, I've been told in one...

Hi R-helpers, I'm new to time series modelling, but my requirement seems to fall just outside the capabilities of the arima function in R. I'd like to fit an ARMA model where the variance of the disturbances is a function of some exogenous variable. So something like: Y_t = a_0 + a_1 * Y_(t-1) +...+ a_p * Y_(t-p) + b_1 * e_(t-1) +...+ b_q * e_(t-q) + e_t, where e_t ~ N(0, sigma^2_t),