Displaying 20 results from an estimated 300 matches similar to: "loops in R help me please"
2013 Jan 03
2
simulation
Dear R users,
suppose we have a random walk such as:
v_t+1 = v_t + e_t+1
where e_t is a normal IID noise pocess with mean = m and standard deviation = sd and v_t is the fundamental value of a stock.
Now suppose I want a trading strategy to be:
x_t+1 = c(v_t – p_t)
where c is a costant.
I know, from the paper where this equations come from (Farmer and Joshi, The price dynamics of common
2010 Sep 28
0
Time invariant coefficients in a time varying coefficients model using dlm package
Dear R-users,
I am trying to estimate a state space model of the form
(1) b_t = G * b_t-1 + w_t w_t ~ N(0,W)
(2) y_t= A' * x_t + H' * b_t + v_t v_t ~ N(0,V)
(Hamilton 1984: 372)
In particular my estimation in state space form looks like
(3) a3_t = 1 * a3_t-1 + w_t w_t ~ N(0,W)
(4) g_t = (a1, a2) * (1, P_t)' + u_t * a3_t + v_t v_t ~ N(0,V)
where g_t is the
2010 Nov 24
0
Seeking advice on dynamic linear models with matrix state variable.
Hello, fellow R users,
I recently need to estimate a dynamic linear model in the following form:
For the measurement equation:
Y_t = F_t * a_t + v_t
where Y_t is the observation. It is a 1 by q row vector for each t.
F_t is my forecasting variable. It is a 1 by p row vector.
a_t is my state variable. It is a p by q MATRIX of parameters with each column of the matrix being regression
2012 Apr 30
2
The constant part of the log-likelihood in StructTS
Dear all,
I'd like to discuss about a possible bug in function StructTS of stats
package. It seems that the function returns wrong value of the
log-likelihood, as the added constant to the relevant part of the
log-likelihood is misspecified. Here is an simple example:
> data(Nile)
> fit <- StructTS(Nile, type = "level")
> fit$loglik
[1] -367.5194
When computing the
2008 May 07
1
dlm with constant terms
Hi,
I am trying to figure how to use dlm with constant terms
(possibly time-dependent) added to both equations
y_t = c_t + F_t\theta_t + v_t
\theta_t = d_t + G_t\theta_{t-1} + w_t,
in the way that S-PLUS Finmetrics does?
Is there any straightforward way to transform the above to
the default setup?
Thanks,
Tsvetan
--------------------------------------------------------
NOTICE: If received in
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
2007 Nov 24
0
Help on State-space modeling
Hi all,
I'm working on a term structure estimation using state-space modeling for
1, 2 and 3 factor models.
When I started to read the functions on R, I got to the function ss on the
library sspir. From what I
understood this function is similar to SsfFit from S-PLUS. But for my models
purpose there is something
left to be desired. Its formulation follow these equations:
*Y_t = F_t^T *
2009 Feb 15
0
Kalman Filter - dlm package
Dear all,
I am currently trying to use the "dlm" package for Kalman filtering.
My model is very simple:
Y_t = F'_t Theta_t + v_t
Theta_t = G_t Theta_t-1 + w_t
v_t ~ N(0,V_t) = N(0,V)
w_t ~ N(0,W_t) = N(0,W)
Y_ t is a univariate time series (1x1)
F_t is a vector of factor returns (Kx1)
Theta_t is the state vector (Kx1)
G_t is the identity matrix
My first
2010 Oct 06
1
dlm package: how to specify state space model?
Dear r-users!
I have another question regarding the dlm package and I would be very
happy if someone could give me a hint!
I am using the dlm package to get estimates for an endogenous rate of
capacity utilization over time. The general form of a state space model
is
(1) b_t = G * b_t-1 + w_t w_t ~ N(0,W)
(2) y_t= A' * x_t + H' * b_t + v_t v_t ~ N(0,V)
(Hamilton 1984: 372)
The
2005 Dec 14
1
Kalman Filter Forecast using 'SSPIR'
Dear R Users,
I am new to state-space modeling. I am using SSPIR
package for Kalman Filter. I have a data set containing one dependent
variable and 7 independent variables with 250 data points. I want to use
Kalman Filter for forecast the future values of the dependent variable
using a multiple regression framework. I have used ssm function to
produce the state space (SS)
2009 Apr 03
1
[LLVMdev] php crash
I tried the version you used, too. the resulting executable was still broken.
I guess the reason is due to fastcall on function pointers, which
Clang does not recognize. Consider the following snippet.
#include <stdio.h>
void __attribute__((fastcall)) f(int i)
{
printf("%d\n", i);
}
typedef void (*__attribute__((fastcall)) f_t)(int i);
//typedef void
2017 Jun 20
1
How to write an estimated seasonal ARIMA model from R output?
I'm trying to use the following command.
arima (x, order = c(p,d,q), seasonal =list(order=c(P,D,Q), period=s)
How can I write an estimated seasonal ARIMA model from the outputs. To be specifically, which sign to use? I know R uses a different signs from S plus.
Is it correct that the model is:
(1-ar1*B-ar2*B^2-...)(1-sar1*B^s-sar2*B^2s-....)(1-B)^d(1-B^s)^D
2005 Jan 21
2
transfer function estimation
Dear all,
I am trying to write an R function that can estimate Transfer functions *with additive noise* i.e.
Y_t = \delta^-1(B)\omega(B)X_{t-b} + N_t
where B is the backward shift operator, b is the delay and N_t is a noisy component that can be modelled as an ARMA process. The parameters to both the impulse response function and the ARMA noisy component need to be estimated simultaneously.
I
2010 Aug 23
1
Fitting a GARCH model in R
Hi,
I want to fit a mean and variance model jointly.
For example I might want to fit an AR(2)-GARCH(1,1) model i.e.
r_t = constant_term1 + b*r_t-1 + c*r_t-2 + a_t
where a_t = sigma_t*epsilon_t
where sigma^2_t = constant_term2 + p*sigma^2_t-1 + q*a^2_t-1
i.e. R estimates a constant_term1, b, c, constant_term2, p, q
TIA
Aditya
2018 May 13
0
(no subject)
> On May 12, 2018, at 9:42 AM, malika yassa via R-help <r-help at r-project.org> wrote:
>
>
> hello
> for exampl, i have this programme
> # Generating data which are right truncated
> library(DTDA)
> library(splines)
> library(survival)
> n<-25
> X<-runif(n,0,1)
> V<-runif(n,0.75,1)
> for (i in 1:n){
> while (X[i]>V[i]){
>
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
2018 May 12
3
(no subject)
hello
for exampl, i have this programme
# Generating data which are right truncated
library(DTDA)
library(splines)
library(survival)
n<-25
X<-runif(n,0,1)
V<-runif(n,0.75,1)
for (i in 1:n){
while (X[i]>V[i]){
X[i]<-runif(1,0,1)
V[i]<-runif(1,0.75,1)
}}
res<-lynden(X=X,U=NA, V=V, boot=TRUE)
attach(res)
temps = time
M_i = n.event
L_t = res
2011 Mar 17
1
generalized mixed linear models, glmmPQL and GLMER give very different results that both do not fit the data well...
Hi,
I have the following type of data: 86 subjects in three independent groups (high power vs low power vs control). Each subject solves 8 reasoning problems of two kinds: conflict problems and noconflict problems. I measure accuracy in solving the reasoning problems. To summarize: binary response, 1 within subject var (TYPE), 1 between subject var (POWER).
I wanted to fit the following model:
2011 Nov 20
2
Continuasly Compunded Returns with quantmod-data
Hey guys,
i want to calculate the continuasly compounded returns for stock prices.
Formula for CCR:
R_t = ln(P_t/P_{t-1})*100
With R:
First i have to modify the vectors, so that they have the same length
and we start at the second observation.
log(GOOG1[-1]/GOOG1[1:length(GOOG1)-1])*100
That does work with normal vectors.
My Questions:
1) I want to use this for stock prices.
so i
2009 Nov 23
3
Translation from R codes to SAS.
my teachers doesnt understand R and I don't know how to use SAS.
Anyone interested in translating my codes to test whether your SAS codes are
as good as R???
I can test it on SAS codes once you have translated it ....
regards:working:
--
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