search for: eta1

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,

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...

...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...

...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(...

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=0… Could you give me more explanation about this method with likelihood ratio and chi-square ? > Can you recast the problem...

...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...

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]]

...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...

...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...

..., 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,...

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

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