Displaying 12 results from an estimated 12 matches for "eta1".
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beta1
2004 Feb 26
2
Structural Equation Model
Hello all!
I want to estimate parameters in a MIMIC model. I have one latent
variable (ksi), four reflexive indicators (y1, y2, y3 and y4) and four
formative indicators (x1, x2, x3, x4). Is there a way to do it in R? I
know there is the SEM library, but it seems not to be possible to
specify formative indicators, that is, observed exogenous variables
which causes the latent variable.
Thanks,
2007 Apr 15
1
Fit sem model with intercept
Hi - I am trying to fit sem model with intercepts. Here is what I have in my model.
Exogeneous vars: x1 (continous), x2 (ordinal), x3 (ordinal), x4(continuous)
Endogeneous vars: y1 (continuous), y2 (ordinal), y3 (ordinal)
SEM model:
x1 -> eta1; x2 -> eta1; x3 -> eta2; x4 -> eta2; eta1 -> y1, eta1 -> y2, eta2 -> y2, eta2 -> y3
However, in these arrow models, I don't know how to add intercept onto it. I am trying to find an example code using sem package on how to incorporate intercept but cannot find any documen...
2009 Apr 21
1
How to compare parameters of non linear fitting curves
...exp(-etaD*cD)) / (1+exp(etaD(t-cD)))
Moreover, when experiments are still active, they may change of state
(from 0 to 1). But they may fall inactive before changing their state
(their state still equals 0). The survival curve of state may also be
fitted with the following model:
f(A)=(1+exp(-eta1*c1)) / (1+exp(eta1(t-c1))) * (1+exp(-etaD*cD)) /
(1+exp(etaD(t-cD)))
I estimate with nlm 1?) values of etaD and cD parameters and 2?)
inject them as constant in the function to be minimized by nlm to
estimate values of eta1 and c1.
I perform these estimations for two different experimental...
2006 Jul 25
1
HELP with NLME
...Any help would be greatly appreciated.I apologize for the
clumsiness of the R code.
Many thanks in advance.
Sincerely,
Loki
#################################################################
SAS Code:
proc nlmixed data=repdat
parms b0 -3 b1 -.135 a0 3 a1 4 sigsq 0.25;
if vs.flag = 1 then do;
eta1 = b0 + b1*lnbldT;
llbin = anybc.cens.ind*eta1 - log(1+exp(eta1));
eta2 = a0 + a1*lnndsTs;
llnorm = -1/(2*sigsq)*(lnbldT - eta2)**2 - .5*log(sigsq);
ll = llbin + llnorm;
end;
else do;
eta2 = a0 + a1*lnndsTs;
eta1 = b0 + b1*eta2 + u;
llbin = anybc.cens.ind*eta1 - log(...
2009 Apr 22
0
Rép : How to compare parameters of non linear fitting curves - COMPLETE REPLY -
Oups, I sent the email by error, as I was still writing my reply…
Spencer,
Le 22-avr.-09 à 03:33, spencerg a écrit :
> Is your first model a special case of the second with eta1 = 0?
> If yes, what about using 2*log(likelihood ratio) being approximately
> chi-square?
Yes, the first model is a special case of the second with eta1=0â¦
Could you give me more explanation about this method with likelihood
ratio and chi-square ?
> Can you recast the problem...
2002 Feb 11
0
profile
...certain ranges of the parameter values.
So now I want to reduce the range of the profiling. I've been looking at the
help page for profile.nls and also I hacked the codes for profile.nls (just
by typing profile.nls), but haven't really found an efficient way to do it.
For say, my parameter eta1, I found that the profiler function works between
-1.6<tau<1.6. I adjusted the code in profile.nls to profile within that
range only (this is a very crude adjustment, see the code below). The new
profile works, and I can increase the number of points profiled (by changing
delta.t), but for so...
2009 Jan 08
3
NY Times article
Sorry if this is spam, but I couldn't see it having popped up on the list
yet.
http://www.nytimes.com/2009/01/07/technology/business-computing/07program.html?emc=eta1
Anand
[[alternative HTML version deleted]]
2008 Nov 26
1
Request for Assistance in R with NonMem
...KA
(0, 4.7) ;CL
(0, 38) ;V
(0.0, .5) ; EMAX
(0.0, 100) ; EC50
(0.0, 1, 10) ; N
$OMEGA
0.04
0.04
0.04
0.04
0.04
0.04
$SIGMA
0.04
5
$ESTIMATION MAXEVAL=9999 NOABORT METHOD=0 POSTHOC PRINT=5
$COVARIANCE
$TABLE ID TIME AGE BW GNDR TVKA TVV TVCL ETA1 ETA2 ETA3
EVID NOPRINT ONEHEADER FILE=TABLE.PAR
$TABLE NOPRINT FILE=../3033.TAB ONEHEADER
ID TIME AGE BW GNDR KA V CL TVKA TVCL TVV FLAG FLA2 EVID EFF CONC IPRED FLAG
$TABLE NOPRINT ONEHEADER FILE=../3033par.TAB
ID TIME AGE BW GNDR KA V CL TVKA TVCL TVV EMAX EC50 ETA1 ETA2 ETA3
EVID
$TABLE ID TIME...
2007 Jul 26
3
substituting dots in the names of the columns (sub, gsub, regexpr)
...sers,
I have the following two problems, related to the function sub, grep,
regexpr and similia.
The header of the file(s) I have to import is like this.
c("y (m)", "BD (g/cm3)", "PR (Mpa)", "Ks (m/s)", "SP g./g.", "P
(m3/m3)", "theta1 (g/g)", "theta2 (g/g)", "AWC (g/g)")
To get rid of spaces and symbols in the names of the columns,
I use read.table(... check.names=TRUE) and I get:
str <- c("y..m.", "BD..g.cm3.", "PR..Mpa.", "Ks..m.s.", "SP.g..g.",
&q...
2012 Mar 23
0
Fixing error variance in a path analysis to model measurement error in scales using sem package
..., gam9
sRU <-> sRU, NA, (1 - alpha(sRU))*(variance(sRU))
pRU <-> pRU, NA, (1 - alpha(pRU))*(variance(pRU))
rRU <-> rRU, NA, (1 - alpha(rRU))*(variance(rRU))
power_alt -> em, iota1
power_alt <-> power_alt, NA, (1 - alpha(power_alt))*(variance(power_alt))
ms_alt -> em, zeta1
ms_alt <-> ms_alt, NA, (1 - alpha(ms_alt))*(variance(ms_alt))
em -> relM1, eta1
em <-> em, NA, (1 - alpha(em))*(variance(em))
relM1 <-> relM1, lam1
After testing this model, the model fits were unnaceptable and package sem
could not compute modification instances. In contrast,...
2005 Aug 12
3
General expression of a unitary matrix
Hi, all,
Does anybody got the most general expression of a unitary matrix?
I found one in the book, four entries of the matrix are:
(cos\theta) exp(j\alpha); -(sin\theta)exp(j(\alpha-\Omega));
(sin\theta)exp(j(\beta+\Omega)); (cos\theta) exp(j\beta);
where "j" is for complex.
However, since for any two unitary matrices, their product should also
be a unitary matrix. When I