similar to: test to compare significant correlation increase

Hi! I have two time series. Both measure the same thing and I would like to determine which one is noisier. Would it be a good measure of the noise in each time series the absolute lag difference? Is this a good measure? Any other measure I could use? Thanks for help :) David Riano Center for Spatial Technologies and Remote Sensing (CSTARS) University of California 250-N, The Barn One Shields

I am trying to use Fisher's z' transformation of the Pearson's r but the standard error does not appear to be correct. I have simulated an example using the R code below. The z' data appears to have a reasonably normal distribution but the standard error given by the formula 1/sqrt(N-3) (from http://davidmlane.com/hyperstat/A98696.html) gives a different results than sd(z). Can

Hi everyone, I want to use the Fisher r-to-z transformation as part of a hypothesis test of r. I can't find an R function that can do that. Am I missing it? -Tim -- Tim Wilson | Visit Sibley online: | Check out: Henry Sibley HS | http://www.isd197.org | http://www.zope.com W. St. Paul, MN | | http://slashdot.org wilson at visi.com | <dtml-var

Dear R users, This is more a statistical question rather than an R question. I'd appreciate it if you can give me some suggestions. I have a sample of a time series (sample size 500, fat tail in density). I am trying to calculate the Standard error of standard deviation of a sub-block-sample (sample size 250). I take 100 this kind of sub-block-sample, randomly. For these 100 subsamples, I

I have 2GB installed on my windows XP box running R 1.9.0, and after performing a prune.tree(intree,newdata), I get an out of memory error within R, but it says the maximum allowed is 1024gb (1/2 of what I have!) Can R not use more than 1GB on an XP box? I noticed I had ~600mb left over after R conked out, so clearly I had more memory... What about virtual memory? --j -- Jonathan Greenberg

I was hoping I could get some help with an import question. I work with remote sensing imagery which commonly comes in binary form in various interleaving formats (byte interleaved by line, by pixel, etc..). These files are 2d spatial x B bands in size, and I want to be able to extract the band values from various pixels (so each line of data into R would be one pixel x B bands). What's the

Hi, based on the sample size I want to calculate whether to correlation coefficients are significantly different or not. I know that as a first step both coefficients have to be converted to z values using fisher's z transformation. I have done this already but I dont know how to further proceed from there. unlike for correlation coefficients I know that the difference for z values is

I have a binary file which is an image with multiple bands, arranged in BSQ format such that R, B and G are all N x M sized matrices (corresponding to Red, Blue and Green colors respectively). The BSQ file arranges the data as [R, B, G], so to access the B matrix, I have to read forward N x M + 1 number of samples. Is there a fast way to define a variable as the B matrix exclusively (e.g. Can I

Hi there -- I downloaded the MacOS X binaries of R and followed the instructions on installing it, and when I go to perform a tree function, I get the error "Error: couldn't find function "tree"". Do I need to somehow preload the function? If so, how do I do that? Also, update.packages() works for some packages, but not all -- it often fails in the compilation. I have

You could calculate the confidence interval of the correlation at your desired df: http://davidmlane.com/hyperstat/B8544.html The below code takes as arguments the observed correlation, N, and alpha, calculates the confidence interval and checks whether this includes 0. cor.test2=function(r,n,a=.05){ phi=function(x){ log((1+x)/(1-x))/2 } inv.phi=function(x){

R-helpers: Are there any ways to auto-generate R-friendly (e.g. will pass a compilation check) .Rd files given a set of .R code? How about GUIs that help properly format the .Rd files? Thanks! I want a basic set of .Rd files that I can update as I go, but as with most things my documentation typically lags behind my coding by a few days. --j -- Jonathan A. Greenberg, PhD Assistant Project

I'm trying to redirect where temporary files go under R to D:\temp\somerandomname from its default (C:\Documents and Settings\username\Temp\somerandomname) -- how do I go about doing this? --j -- Jonathan A. Greenberg, PhD Postdoctoral Scholar Center for Spatial Technologies and Remote Sensing (CSTARS) University of California, Davis One Shields Avenue The Barn, Room 250N Davis, CA 95616

Quick question -- if I have a vector of strings that I'd like to split into two new vectors based on a substring that is inside of each string, what is the most efficient way to do this? The substring that I want to split on is multiple characters, if that matters, and it is contained in every element of the character vector. --j -- Jonathan A. Greenberg, PhD Postdoctoral Scholar

I have a numerical vector which contains a (poorly) formatted time column, which, in theory, should be HHMM, but was distributed as an integer, so, for 12:15 am, it is saved as "15" (e.g. HHMM = 0015 with the zeroes stripped). I'm trying to use this in conjunction with strptime, but I'm thinking because each time is an integer ranging from 1 to 4 digits, I probably need to

Quick informal poll: what is everyone's favorite text editor for working with R? I'd like to hear from people who are using editors that have some level of direct R interface (e.g. Tinn-R, Komodo+SciViews). Thanks! --j -- Jonathan A. Greenberg, PhD Postdoctoral Scholar Center for Spatial Technologies and Remote Sensing (CSTARS) University of California, Davis One Shields Avenue The

Hopefully this is a pretty easy fix -- I need to have R query the path separator for some code I'm trying to write (it involves using a system() call) -- the call requires a path and a wildcard, e.g.: command="mycommand /path/to/*.files" in the case of unix or, command="mycommand.exe C:\\path\\to\\*.files" on a windows box System.which is working correctly, so the

Rers: I have some ecological data (stream velocity vs. % cover of submerged weeds) that shows strong evidence of a thresholding step-function, e.g. below some velocity, % cover ranges from 0% to 100% (with no apparent relationship to velocity within this range of velocities), but above a certain "threshold" velocity, the % cover does not appear to exceed, say, 10%. There are good

R'ers: I was hoping I could get some direction on this. I have a dataset of the form: Y1,Y2,...,YM = f(X1,X2,...,XN), where N is >>> M The response data (Y1,Y2,...,YM) is frequency data, such that the sum of all Yi = 1.0. Both Xj and Yi are continuous variables. I'm trying to figure out the best approach(es) to solving for the model f() -- any ideas? I could solve

I'm trying to hunt down an appropriate kriging package for my specific application, and I was hoping someone on the R list might have some pointers -- I'm interested in performing kriging and related spatial interpolations with one of the R packages, but I need to be able to provide my own point-to-point distances (e.g. I do not want to use standard between point distances, as calculated

R-helpers: I'm working on an r-package that I want to make as easy-to-use as possible for a novice R-user, which includes automatically installing required packages. I, myself, am a novice R-packager, so the solution I came up with was to embed: print("Loading required packages...") if (!require("reshape")) { install.packages("reshape") } if