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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)" ""
[8,] "y_{01}(k-001)" "y_{01}...
2015 Feb 03
2
Seed in 'parallel' vignette
...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 'increasing' indices, so should
rather be "(x_{n-2}, x_{n-1}, x_n, y_{n-2}, y_{n-1}, y_n)" (or, even
more intuitively, "(x_{n-3}, x_{n-2}, x_{n-1}, y_{n-3}, y_{n-2},
y_{n-1})"). The...
2015 Mar 08
0
Seed in 'parallel' vignette
...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 'increasing' indices, so should
> rather be "(x_{n-2}, x_{n-1}, x_n, y_{n-2}, y_{n-1}, y_n)" (or, even
> more intuitively, "(x_{n-3}, x_{n-2}, x_{n-1}, y_{n-3}, y_{n-2},
>...
2012 Jul 28
4
quantreg Wald-Test
...do not know how to tell
R what I want it to do^^
My situation is as follows: I have a data set containing a (dependent)
vector Y and the regressor X. My aim is to check whether the two variables
do not granger-cause each other in quantiles. I started to compute via
quantreg for a single tau:= q:
rq(Y_t~Y_(t-1)+Y_(t-2)+...+X_(t-1)+X_(t-2)+...,tau=q)
This gives me the quantile regression coefficients. Now I want to check
whether all the coefficients of X are equal to zero (for this specific tau).
Can I do this by applying rq.anova ? I have already asked a similiar
question but I am not sure if an...
2001 Jul 20
3
estimation of drift of continuous random walk
...have the following problem to solve and I wonder if there are means in R
that can help me.
At irregular time intervals I observe a random walk process, Y, with
time-varying drift. I assume that the drift, D, is a (linear) function of
some parameter X. The goal is to estimate D(X).
I could regress Y_{t+dt} - Y_{t} ~ X, but it's probably not appropriate
since Var(Y_{t+dt} - Y_{t}) is not constant (actually in theory it is
proportional to dt).
Any suggestions?
Thank you,
Vadim
--------------------------------------------------
DISCLAIMER
This e-mail, and any attachments thereto, is inten...
2009 May 30
0
improve efficiency of a loop
Dear All:
I need advice about efficient looping/vectorization. I am trying to
bootstrap a regression model with one lag of the dependent variable in
the RHS. Specifically, let error^b_(t) be the bootstrapped error of
the regression y_(t) = gamma y_(t-1) + beta x +error_(t) at time (t),
y_(t) is the original dependent variable, and y^b_(t) the bootstraped
y_(t) using parameter estimates gamma and beta. My basic procedure is
like this:
1. Get the first y^b value using y_(1):
y^b_(2) = gamma y_(1) + beta x_(2) + error_(2).b
2. Get...
2006 Apr 29
1
SSPIR problem
...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 appreciated. I am running R version 2.3, on
Windows XP Professional.
> library(sspir)
>
> # Create observation vector
> y_ <- cbind(rep(1, 20), rep(2, 20))
>
> mat <- rbind(c(1, 2), c(3, 4))
>
> #####################################################################
> # Create model
> model <- SS(y = matrix(y_),
+ Fmat = function(tt, x, phi) {
+ FM <- mat
+...
2002 Mar 29
1
help with lme function
Hi all,
I have some difficulties with the lme function and so this is my problem.
Supoose i have the following model
y_(ijk)=beta_j + e_i + epsilon_(ijk)
where beta_j are fixed effects, e_i is a random effect and
epsilon_(ijk) is the error.
If i want to estimate a such model, i execute
>lme(y~vec.J , random~1 |vec .I )
where y is the vector of my data, vec.J is a factor object and vec.I
is the vector for...
2009 Nov 15
2
lme model specification
.... . .
. . . .
. . . .
2000 1 1 5.12
2000 1 2 2.87
2000 1 3 7.23
. . . .
. . . .
. . . .
2000 4 1 2.48
2000 4 2 3.93
2000 4 3 5.17
that is, I have data Y_{gtr} for g (gene) =1,...,2000 t (treatment) = 1,...,4 and r (replicate) = 1,...,3
I would like to fit the following linear mixed model using lme
Y_{gtr} = \mu_{g} + W_{gt} + Z_{gtr}
where the \mu_{g}'s are fixed gene effects, W_{gt} ~ N(0, \sigma^{2}) gene-treatment interactions, and...
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 t...
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
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),
and with the variance specified by something like
sigma^2_t = exp(beta_t * X_t),
where X_t is my exogenous variable. I would be very grateful if somebody
could point me in the di...
2003 Nov 10
1
ts package function filter: mismatch between function action and help (PR#5017)
...sides = 2, circular = FALSE, init)
# init: for recursive filters only. Specifies the initial values of
# the time series just prior to the start value, in reverse
# time order. The default is a set of zeros.
but looks as if it should be in usual order as x is e.g.
init y_0 y_-1 y_-2: 3, 2, 1
filter f_1 f_2 f_3: 1, .5, .25
x: 4, 5, 6, 7, 8
y_1 = 4 + 1*3 + .5*2 + .25*1 = 8.25
y_2 = 5 + 1*8.25 + .5*3 + .25*2 = 15.25
...
but
> filter(4:8,c(1,.5,.25),method="recursive", init=3:1)
Time Series:
Start = 1
End = 5
Frequency = 1
[1] 6.7500 12.7500 22.3750 37...
2001 Oct 09
1
PROC MIXED user trying to use (n)lme...
...nce 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
estimated variance matrix when typing the name of the lme-object,
but that does not give me a "handle" on the matrix.
2) I am trying to fit a mixed model, say
y_{ij} = X_{ij}\beta + U_i + e_{ij}
where Y_{ij}, U_i and e_{ij} all are D-dimensional, and U_i ~
N_D(0,G), and e_{ij} ~ N(0,R). This is easy to do in proc mixed by
including a factor keeping track of how the elements of y_{ij} are
"stacked" on top of each other. This factor is then used in...
2003 Jun 19
2
Fitting particular repeated measures model with lme()
...e in which the
"teacher effect" applies to only one year. One can think of the first
score on the student as a score from a prior year (for which I have no
teacher links), and the second score is from the current year and is
linked to the teacher. The model for student j in class i is:
Y_{ij0} = a_0 + e_{ij0}
Y_{ij1} = a_1 + b_i + e_{ij1}
with Var(b_i) the teacher variance component and Cov(e_{ij0},e_{ij1})
unstructured. That is, if the data are organized by student, the "Z"
matrix in the usual linear mixed model notation has every other row
equal to a row of zeros.
I a...
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 y_{t-1}^2
I looked through documentation of garchFit() from the fGarch library but
didn't find a way to...
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
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2013 Jul 26
0
[LLVMdev] floor
Here is a test case:
extern double floor(double);
extern double floor_(double);
double x = 1.5;
double y, y_;
void foo() {
double y = floor(x);
double y_ = floor_(x);
}
If I compile this for Mips16, it calls the proper helper function for
floor_ but not for floor, because the signature for floor in callee info
is wrong. Args[0] = void RetTy = void
/local/llvmpb_config/install/bin/clang -targe...
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 matrix with
elements equal...
2013 Jul 26
2
[LLVMdev] floor
I'm getting some problems because it seems that the compiler is treating
"floor" differently from other math library functions like "sin".
The Args and RetVal have the parameter and return types marked as void.
For mips16, it's important that I be able to know the original signature
for floating point functions.
In some cases, need to create calls to helper