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see nlm or optim Justin BEM Elève Ingénieur Statisticien Economiste BP 294 Yaoundé. Tél (00237)9597295. ----- Message d'origine ---- De : Wayne Delport <wdelport@botzoo.uct.ac.za> À : r-help@stat.math.ethz.ch Envoyé le : Vendredi, 8 Décembre 2006, 8h27mn 44s Objet : [R] formula format for parameter estimation Hello, I am trying to input the following formula into R for parameter estimation. I don't quite have the just of formula syntax. I understand simp...

Dear all I have a dataset that looks like: fr.wt site 1 4400 glen 2 235 glen 3 225 glen ' ' ' ' ' ' ' ' ' 82 550 glen 83 550 kom 84 550 kom ' ' ' ' ' ' ' ' ' 191 820 kom 192 2000 soet ' ' ' ' ' ' I need to do a series of histograms for each of the codes, levels or factors in

Dear all I have the following data (a shortened extract shown; some replictates of time deleted) to which I fitted the linear model given below: time group mass 11 control 0.019 11 control 0.014 14 control 0.0306 14 control 0.0289 14 control 0.0236 17 control 0.0469 17 control 0.0709 11 five 0.0077 11 five

Dear all I have a question regarding repeating a series of nested ANOVAs. The model is: fit <- aov(response ~ treatment + plot/rep) Treatment has three levels, there are three plots and each plot has four replicates. Now, the experiment was also repeated six times during the year. Ideally I would have liked to include sampling time (month) as an additional factor in the analysis, but

Dear all Is there any way of doing a Tukey HSD post-hoc test after a Kruskal- Wallis or Friedman rank sum test (in the ctest package)? Thanks in advance, Albertus Dr. Albertus J. Smit Department of Botany University of Cape Town Private Bag Rondebosch 7700 South Africa Tel. +27 21 689 3032

Hello, I am trying to input the following formula into R for parameter estimation. I don't quite have the just of formula syntax. I understand simple basic regression (y ~ x), but how do I do the ff: y = ( b0*x )/(x + b1), where b0 and b1 are parameters that need to be solved. Any help/suggestions for a newbie would be much appreciated. thanks ./w Wayne Delport Molecular Ecology and

Dear all I have made some lattice graphs (bwplot(dead ~ treat | group,...). 'group' is a factor with three levels (Artemia larvae, Abalone larvae and Abalone spat), and the result is a graph with three panels corresponding to the levels in 'group', ordered in alphabetical order from bottom to top, as expected. How does one re-order the order in which the levels of

Dear all I need to obtain an estimate of the 50% lethal dose (LD50) from a logistic regression model obtained by applying the glm procedure to some binomial data. The model appears to fit the data very well. I used dope.p from MASS to try and find LD50. The following output appears: > dose.p(iso.glm.logit, cf = c(1,3), p = 1:3/4) Error in dose.p(iso.glm.logit, cf = c(1, 3), p = 1:3/4) :