Displaying 5 results from an estimated 5 matches for "fm2dnase1".
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fm1dnase1
2007 May 31
1
predict.nls - gives error but only on some nls objects
Dear list,
I have encountered a problem with predict.nls (Windows XP, R.2.5.0), but I am not sure if it is a bug...
On the nls man page, an example is:
DNase1 <- subset(DNase, Run == 1)
fm2DNase1 <- nls(density ~ 1/(1 + exp((xmid - log(conc))/scal)),
data = DNase1,
start = list(xmid = 0, scal = 1))
alg = "plinear", trace = TRUE)
Now consider prediction:
> predict(fm2DNase1)
[1] 0.001424337 0.001424337 0.028883648 0.02888...
2012 Sep 19
0
Discrepancies in weighted nonlinear least squares
...m 'nls'):
DNase1 <- subset(DNase, Run == 1)
fm1DNase1 <- nls(density ~ SSlogis(log(conc), Asym, xmid, scal), DNase1)
This is the unweighted fit, in the code of 'nls' one can see that 'nls'
generates a vector wts <- rep(1, n).
Now for a weighted fit:
fm2DNase1 <- nls(density ~ SSlogis(log(conc), Asym, xmid, scal), DNase1,
weights = rep(1:8, each = 2))
in which I assign dcreasing weights for each of the 8 concentrations with 2
replicates.
Now with 'deviance' I get:
> deviance(fm1DNase1)
[1] 0.004789569
> deviance(fm2DNase1...
2013 Feb 12
0
Deviance and AIC in weighted NLS
...I encounter some discrepancies when comparing the deviance of a weighted and
unweigthed model with the AIC values. A general example (from 'nls'):
DNase1 <- subset(DNase, Run == 1)
fm1DNase1 <- nls(density ~ SSlogis(log(conc), Asym, xmid, scal), DNase1)
Now for a weighted fit:
fm2DNase1 <- nls(density ~ SSlogis(log(conc), Asym, xmid, scal),
DNase1, weights = rep(1:8, each = 2))
in which I assign increasing weights for each of the 8 concentrations with 2
replicates.
Now with deviance I get:
> deviance(fm1DNase1)
[1] 0.004789569
> deviance(fm2DNase1)...
2006 Sep 11
4
syntax of nlme
...bject
? I thought it would be a mixture of nls and lme.
after trying very hard, I ask for help on using nlme.
Can someone hint me to some examples?
I constructed a try using the example from nls:
#variables are density, conc and Run
#all works fine with nls
DNase1 <- subset(DNase, Run == 1 )
fm2DNase1 <- nls( density ~ 1/(1 + exp((xmid - log(conc))/scal)),
data = DNase1,
start = list(xmid = 0, scal = 1),
trace = TRUE)
#Now I want to do a mixed model with covariate Run
#how is the syntax?
DNase12 <- subset(DNase, Run == 1 | Run == 2)...
2000 Feb 14
2
Error in the inverse of a diagonal matrix?
I?m new to R so maybe this issue has been asked before and I still could not read the complete set of past messages sent to the list.
I found a weird behabiour that I will explain with a simple example. Lets consider the following block of commands:
> x <- diag(c(1,4,10))
> x
[,1] [,2] [,3]
[1,] 1 0 0
[2,] 0 4 0
[3,] 0 0 10
> invx <- x^-1
> invx