Displaying 20 results from an estimated 3000 matches similar to: "quantreg Wald-Test"
2012 May 28
2
R quantreg anova: How to change summary se-type
He folks=)
I want to check whether a coefficient has an impact on a quantile regression
(by applying the sup-wald test for a given quantile range [0.05,0.95].
Therefore I am doing the following calculations:
a=0;
for (i in 5:95/100){
fitrestricted=rq(Y~X1+X2,tau=i)
tifunrestrited=rq(Y~X1+X2+X3,tau=i)
a[i]=anova(fitrestricted,fitunrestricted)$table$Tn) #gives the Test-Value
}
supW=max(a)
As anova
2015 Feb 03
2
Seed in 'parallel' vignette
Hi,
This is most likely only a minor technicality, but I saw the
following: On page 6 of the 'parallel' vignette
(http://stat.ethz.ch/R-manual/R-devel/library/parallel/doc/parallel.pdf),
the random-number generator "L'Ecuyer-CMRG" is said to have seed
"(x_n, x_{n-1}, x_{n-2}, y_n, y_{n-1}, y_{n-2})". However, in L'Ecuyer
et al. (2002), the seed is given with
2011 Dec 01
1
Estimation of AR(1) Model with Markov Switching
Dear R users,
I have been trying to obtain the MLE of the following model
state 0: y_t = 2 + 0.5 * y_{t-1} + e_t
state 1: y_t = 0.5 + 0.9 * y_{t-1} + e_t
where e_t ~ iidN(0,1)
transition probability between states is 0.2
I've generated some fake data and tried to estimate the parameters using the
constrOptim() function but I can't get sensible answers using it. I've tried
using
2006 Apr 29
1
SSPIR problem
I am having a problem with the package SSPIR. The code below
illustrates it. I keep getting the message: "Error in y - f :
non-conformable arrays."
I tried to tweak the code below in many different ways, for example,
substituting rbind for cbind, and sometimes I get a different error
message, but I could not find a variation of this code that would
work.
Any help will be greatly
2002 Apr 09
2
Restricted Least Squares
Hi,
I need help regarding estimating a linear model where restrictions are imposed on the coefficients. An example is as follows:
Y_{t+2}=a1Y_{t+1} + a2 Y_t + b x_t + e_t
restriction
a1+ a2 =1
Is there a function or a package that can estimate the coefficient of a model like this? I want to estimate the coefficients rather than test them.
Thank you for your help
Ahmad Abu Hammour
--------------
2011 Nov 12
1
State space model
Hi,
I'm trying to estimate the parameters of a state space model of the
following form
measurement eq:
z_t = a + b*y_t + eps_t
transition eq
y_t+h = (I -exp(-hL))theta + exp(-hL)y_t+ eta_{t+h}.
The problem is that the distribution of the innovations of the transition
equation depend on the previous value of the state variable.
To be exact: y_t|y_{t-1} ~N(mu, Q_t) where Q is a diagonal
2007 Mar 05
1
Heteroskedastic Time Series
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),
2002 Apr 19
4
Durbin-Watson test in packages "car" and "lmtest"
Hi,
P-values in Durbin-Watson test obtained through the use of functions available in packages "lmtest" and "car" are different. The difference is quite significant. function "dwtest" in "lmtest" is much faster than "burbinwatson" in "car". Actually, you can take a nap while the latter trying to calculated Durbin-Watson test. My question
2004 Jan 14
3
How can I test if time series residuals' are uncorrelated ?
Ok I made Jarque-Bera test to the residuals (merv.reg$residual)
library(tseries)
jarque.bera.test(merv.reg$residual)
X-squared = 1772.369, df = 2, p-value = < 2.2e-16
And I reject the null hypotesis (H0: merv.reg$residual are normally
distributed)
So I know that:
1 - merv.reg$residual aren't independently distributed (Box-Ljung test)
2 - merv.reg$residual aren't indentically
2009 Jun 19
1
using garchFit() to fit ARMA+GARCH model with exogeneous variables
Hello -
Here's what I'm trying to do. I want to fit a time series y with
ARMA(1,1) + GARCH(1,1), there are also an exogeneous variable x which I
wish to include, so the whole equation looks like:
y_t - \phi y_{t-1} = \sigma_t \epsilon_t + \theta \sigma_{t-1}
\epsilon_{t-1} + c x_t where \epsilon_t are i.i.d. random
variables
\sigma_t^2 = omega + \alpha \sigma_{t-1}^2 + \beta
2000 Apr 04
0
stochastic process transition probabilities estimation
Hi all,
I'm new with R (and S), and relatively new to statistics (I'm a
computer scientist), so I ask sorry in advance if my question is silly.
My problem is this: I have a (sample of a) discrete time stochastic
process {X_t} and I want to estimate
Pr{ X_t | X_{t-l_1}, X_{t-l_2}, ..., X_{t-l_k} }
where l_1, l_2, ..., l_k are some fixed time lags. It will be enough for
me to compute
2001 Oct 09
1
PROC MIXED user trying to use (n)lme...
Dear R-users
Coming from a proc mixed (SAS) background I am trying to get into
the use of (n)lme.
In this connection, I have some (presumably stupid) questions
which I am sure someone out there can answer:
1) With proc mixed it is easy to get a hold on the estimated
variance parameters as they can be put out into a SAS data set.
How do I do the same with lme-objects? For example, I can see the
2001 Nov 19
1
more on acf mis-feature (PR#1177)
At Mon, 19 Nov 2001 08:36:38, you wrote:
> I get the labels I expect: if this is quarterly data the lags are labelled
> in years. That is what `frequency = 4' is intended to mean: 4
> observations per unit of time.
some further thoughts convinces me that this is a mis-feature. if you
ask any person what is the lag i autocorrelation, the answer would be
corr(y_t, y_{t-i}). so you
2005 Jun 14
1
within and between subject calculation
Dear helpers in this forum,
I have the following question:
Suppose I have the following data set:
id x y
023 1 2
023 2 5
023 4 6
023 5 7
412 2 5
412 3 4
412 4 6
412 7 9
220 5 7
220 4 8
220 9 8
......
and i want to calculate sum_{i=1}^k
sum_{j=1}^{n_i}x_{ij}*y_{ij}
is there a simple way to do this within and between
subject summation in R?
2005 Jun 15
2
need help on computing double summation
Dear helpers in this forum,
This is a clarified version of my previous
questions in this forum. I really need your generous
help on this issue.
> Suppose I have the following data set:
>
> id x y
> 023 1 2
> 023 2 5
> 023 4 6
> 023 5 7
> 412 2 5
> 412 3 4
> 412 4 6
> 412 7 9
> 220 5 7
> 220 4 8
> 220 9 8
> ......
>
Now I want to compute the
2003 Aug 30
1
3D plot of a bivariate normal distribution
Hi,
I've used the Mathematica to produce 3D graphics, contour plots of a
bivariate normal distribution
Now I want make these graphics in R, but i do not know how.
I would like to:
- Plot a 3D graph for some different variance matrix
- Plot the contour plots
- Find and try to plot (in the 3d graph ou contour plot) the (1-a)%
confidence region based in a chi-square(a) with the degrees of
2000 Sep 22
0
what do you do for 2SLS or 3SLS
For 2 or 3 stage least squares, what do you R folks do?
Follow-up question. My student wants to estimate this. 2 variables are
governed by a system of difference equations. His theory is like so.
Y_t and X_t are
state variables, we want estimates for a, g, b, and h.
X_(t+1) = 1 + a X_t + (a/K)* (X_t)^2 - g Y_t X_t
Y_(t+1) = b Y_t + h* X_t * Y_t
K is perhaps something to estimate, but it
2011 Aug 18
2
Concatenate two strings in one in a string matrix
Dear R-Users
I have the following matrix
> out$desc [,1] [,2]
[1,] "" ""
[2,] "y_{01}(k-001)" ""
[3,] "y_{01}(k-002)" ""
[4,] "y_{01}(k-003)" ""
[5,] "u_{01}(k-001)" ""
[6,] "u_{01}(k-002)" ""
[7,] "u_{01}(k-003)" ""
2015 Mar 08
0
Seed in 'parallel' vignette
On Tue, Feb 3, 2015 at 10:39 AM, Marius Hofert
<marius.hofert at uwaterloo.ca> wrote:
> Hi,
>
> This is most likely only a minor technicality, but I saw the
> following: On page 6 of the 'parallel' vignette
> (http://stat.ethz.ch/R-manual/R-devel/library/parallel/doc/parallel.pdf),
> the random-number generator "L'Ecuyer-CMRG" is said to have seed
>
2013 Feb 05
1
R -HELP REQUEST
Good morning to you all,
Sorry for taking your time from your research and
teaching schedules.
If you have a non-stationary univariate time Series
data that has the transformation:
Say; l.dat<-log (series)
d.ldat<-diff (l.dat, differences=1)
and you fit say arima model.
predit.arima<-predict (fit.series, n.ahead=10,
xregnew= (n+1) :( n+10))
How could I re-transform