[R] irt model estimation with constrained parameters

hi, is there a way to estimate the parameters of an IRT model (in my case, the graded response model), when some item parameter are already known? what i have heard is that other irt programs such as parscale allow to prespecify some of the item difficulty and location parameters and estimate o

Re: [R] starting values in glm(..., family = binomial(link =log))

imple mind like mine? Best, Felix Von: Ravi Varadhan [mailto:ravi.varad...@jhu.edu] Gesendet: Mittwoch, 30. Januar 2013 17:02 An: Fischer, Felix Cc: r-help@r-project.org Betreff: [R] starting values in glm(..., family = binomial(link =log)) Try this: Age_log_model = glm(Arthrose ~ Alter, d

[R] starting values in glm(..., family = binomial(link = log))

Dear R-helpers, i have a problem with a glm-model. I am trying to fit models with the log as link function instead of the logit. However, in some cases glm fails to estimate those models and suggests to give start values. However, when I set start = coef(logistic_model) within the function call

Re: [R] identify time span in date vector

ht- Von: David Winsemius [mailto:dwinsem...@comcast.net] Gesendet: Dienstag, 3. April 2012 19:08 An: Fischer, Felix Cc: r-help@r-project.org Betreff: Re: [R] identify time span in date vector On Apr 3, 2012, at 9:35 AM, Fischer, Felix wrote: > Hello everyone, > > i try to identify

Re: [R] identify time span in date vector

det: Mittwoch, 4. April 2012 09:47 An: Fischer, Felix Cc: r-help@r-project.org Betreff: Odp: [R] identify time span in date vector Hi Can you please be more specific? Based on this input, what do you want as a result? > set.seed(111) > dates = as.Date(sort(rnorm(10,3000,100)), origin =

[R] identify time span in date vector

Hello everyone, i try to identify the first element of a date vector, for which the following condition holds: at least 3 more dates within the next 365 days, but at least one of these must be between 3-12 month later. dates = as.Date(sort(rnorm(10,3000,100)), origin = "2000-1-1") Has anyone a

[R] convert sas date format

Hi everybody, i have a csv-file, containing dates in an akward sas format, where 31.12.1559 is -1, 1.1.1960 is 1, 2.1.1960 is 2 and so on (see http://www.sfu.ca/sasdoc/sashtml/lrcon/zenid-63.htm ). Is there any function in R to convert this into -M-D easily? Best, Felix Dr. rer. nat. Dipl

Re: [R] break error bars in ggplot2

ov 2011 13:44:44 + Fischer, Felix charite.de> writes: > > Hello, <http://tolstoy.newcastle.edu.au/R/e16/help/11/11/1444.html#1454qlink1> > > i use ggplot to plot some measures including CIs as horizontal > errorbars. I get an error when the scale > limits are narrow

[R] break error bars in ggplot2

Hello, i use ggplot to plot some measures including CIs as horizontal errorbars. I get an error when the scale limits are narrower than the boundaries of the error bar and hence the CIs are not plotted. library(ggplot2) df <- data.frame(resp=c(1,2), k=c(1,2), se=c(1,2)) ggplot(df, aes(resp,y=k

Re: [R] Bootstrapping a repeated measures ANOVA

Thank you for your answer. Sorry for the missing example. In fact, i think, i solved the issue by some data-manipulations in the function. I splitted the data (one set for each measuring time), selected the cases at random, and then combined the two measuring times again. Results look promisin

[R] Bootstrapping a repeated measures ANOVA

Hello everyone, i have a question regarding the sampling process in boot(). I try to bootstrap F-values for a repeated measures ANOVA to get a confidence interval of F-values. Unfortunately, while the aov works fine, it fails in the boot()-function. I think the problem might be that the resampl