Re: [R] statistical question

2011-03-31 Thread Greg Snow
g > Subject: [R] statistical question > > Dear List! > > I want to compare medians of non normal distributed data. Is it > possible and usefull to calculate 95% confidence intervals for > medians? And if so - how can this be achieved in R? > > Thanks a lot! > Anna &g

Re: [R] statistical question

2011-03-31 Thread Roger Koenker
The default rank test in the quantreg package would look like this summary(rq(y ~ d, tau = .5)) where d is a factor variable indicating which sample the elements of y belonged to. Summary returns a confidence interval for the coef of the factor variable -- if this interval excludes zero at the c

[R] statistical question

2011-03-31 Thread Anna Lee
Dear List! I want to compare medians of non normal distributed data. Is it possible and usefull to calculate 95% confidence intervals for medians? And if so - how can this be achieved in R? Thanks a lot! Anna -- Der Inhalt dieser E-Mail ist vertraulich. Sollte Ihnen die E-Mail irrtümlich zu

Re: [R] Statistical question and implementation

2009-12-10 Thread David Winsemius
On Dec 10, 2009, at 10:59 AM, Santosh wrote: Dear R/Statistics-gurus! I tried to find answer to my hypothetical question and in vain. Sorry, I don't have a dataset that fits into this hypothetical question and pardon me if my explanations/use of statistical terms are not accurate. It doe

[R] Statistical question and implementation

2009-12-10 Thread Santosh
Dear R/Statistics-gurus! I tried to find answer to my hypothetical question and in vain. Sorry, I don't have a dataset that fits into this hypothetical question and pardon me if my explanations/use of statistical terms are not accurate. It does sound a weird question, but I want to rule out that

Re: [R] Statistical question about logistic regression simulation

2009-08-26 Thread Ravi Varadhan
[mailto:r-help-boun...@r-project.org] On Behalf Of Denis Aydin Sent: Wednesday, August 26, 2009 10:18 AM To: r-help@r-project.org Subject: [R] Statistical question about logistic regression simulation Hi R help list I'm simulating logistic regression data with a specified odds ratio (beta) and

Re: [R] Statistical question about logistic regression simulatio

2009-08-26 Thread Ted Harding
On 26-Aug-09 14:17:40, Denis Aydin wrote: > Hi R help list > I'm simulating logistic regression data with a specified odds ratio > (beta) and have a problem/unexpected behaviour that occurs. > > The datasets includes a lognormal exposure and diseased and healthy > subjects. > > Here is my loop:

[R] Statistical question about logistic regression simulation

2009-08-26 Thread Denis Aydin
Hi R help list I'm simulating logistic regression data with a specified odds ratio (beta) and have a problem/unexpected behaviour that occurs. The datasets includes a lognormal exposure and diseased and healthy subjects. Here is my loop: ors <- vector() for(i in 1:200){ # First, I creat

[R] statistical question: confidence interval of regression weight - significance

2009-03-07 Thread Martin Batholdy
hi, at first; thanks for the help on getting confidence intervals in R. now I have a pure statistical question. I hope you don't mind if I ask ... I have an expectation of how large my beta-weight in a regression should be - so I have an "ideal" or expected regression line. Now the real

Re: [R] Statistical question: one-sample binomial test for clustered data

2008-11-25 Thread Thomas Lumley
The bootstrap that Greg Snow suggested is probably the best approach, but it is possible to estimate the variance of the proportion. The total T number of yes reponses is the sum of twenty totals for blocks, and these are independent, so the variance of Y is 20 times the variance of these tw

Re: [R] Statistical question: one-sample binomial test for clustered data

2008-11-25 Thread Greg Snow
Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > project.org] On Behalf Of Matthias Gondan > Sent: Tuesday, November 25, 2008 7:53 AM > To: [EMAIL PROTECTED] > Subject: [R] Statistical question: one-sample binomial test for > clustered data > > Dear list, >

[R] Statistical question: one-sample binomial test for clustered data

2008-11-25 Thread Matthias Gondan
Dear list, I hope the topic is of sufficient interest, because it is not R-related. I have N=100 yes/no-responses from a psychophysics paradigm (say Y Yes and 100-Y No-Responses). I want to see whether these yes-no-responses are in line with a model predicting a certain amount p of yes-responses.

Re: [R] Statistical question re assessing fit of distribution functions.

2008-09-23 Thread David Scott
On Tue, 23 Sep 2008, Ted Byers wrote: Thanks Timur While assessing whether or not the best option would be a normal distribution (it won't be, the data in this case LOOKS more poisson, or if I explude the first week of results, a negative exponential; and in my other case, cauchy is more likel

Re: [R] Statistical question re assessing fit of distribution functions.

2008-09-23 Thread Ted Byers
Thanks Timur While assessing whether or not the best option would be a normal distribution (it won't be, the data in this case LOOKS more poisson, or if I explude the first week of results, a negative exponential; and in my other case, cauchy is more likely), I really need a test that can be appl

Re: [R] Statistical question re assessing fit of distribution functions.

2008-09-22 Thread Timur Shtatland
If one of the goals is the normality test, then there may be better alternatives to the Kolmogorov-Smirnov test. See an explanation on: http://graphpad.com/FAQ/viewfaq.cfm?faq=959 The R implementation: ?shapiro.test A casual search also turned this up: http://tolstoy.newcastle.edu.au/R/help/04/09

[R] Statistical question re assessing fit of distribution functions.

2008-09-22 Thread Ted Byers
I am in a situation where I have to fit a distrution, such as cauchy or normal, to an empirical dataset. Well and good, that is easy. But I wanted to assess just how good the fit is, using ks.test. I am concerned about the following note in the docs (about the example provided): "Note that the