Displaying 3 results from an estimated 3 matches for "logec50".
2010 Oct 11
2
Nonlinear Regression Parameter Shared Across Multiple Data Sets
I'm working with 3 different data sets and applying this non-linear
regression formula to each of them.
nls(Y ~ (upper)/(1+10^(X-LOGEC50)), data=std_no_outliers,
start=list(upper=max(std_no_outliers$Y),LOGEC50=-8.5))
Previously, all of the regressions were calculated in Prism, but I'd like to
be able to automate the calculation process in a script, which is why I'm
trying to move to R. The issue I'm running into is that...
2009 Jun 17
0
nls with weights
...Further, I'd like to know, why I get an error message, if I change the
bottom-parameter to min(yData)??? Can anybody explain, why it ends up with:
"singular gradient"
8< ------------------------------------------------------- >8
sigmoid <- function(x, bottom, top, slope, logec50) { bottom + (top -
bottom) / (1 + 10^((logec50-x)*slope)) }
xData <- seq(-10,10,1.2)
yData1 <- sigmoid(xData,10,1,-0.2,3) + rnorm(1:length(xData), sd = 0.5)
yData2 <- sigmoid(xData,10,1,-0.2,3) + rnorm(1:length(xData), sd = 0.2)
yData3 <- sigmoid(xData,10,1,-0.2,3) + rnorm(1:length(x...
2010 Oct 15
0
nomianl response model
...l.gmail.com>
Content-Type: text/plain
As an addendum to my question, I'm attempting to apply the solution to the
robust non-linear regression function nlrob from the robustbase package, and
it doesn't work in that situation. I'm getting
allRobustFit <- nlrob(Y ~ (upper)/(1+10^(X-LOGEC50[dset])), data=all
,start=list(upper=max(all$Y),LOGEC50=c(-8.5,-8.5,-8.5)))
Error in nls(formula, data = data, start = start, algorithm = algorithm, :
parameters without starting value in 'data': LOGEC50
I'm guessing this is because the nlrob function doesn't know what to do with...