Displaying 20 results from an estimated 3000 matches similar to: "Test if beta is different from something other than 0"
2002 Nov 22
3
simple test on slope of lm()
Hello
I want to compare the slope (let's say 'b') of a linear model obtained
with lm() to a theoretical value (let's say 'th').
To do so, I think I should compute a 't value' using
something like :
(b - 'th')/standard.deviation(b)
and then look at the p-value of this computed t.
I don't understand how to do this in a simple way, just using lm()
2004 Jun 05
3
'cygpath -d' to fix windows paths with spaces
The cygwin 'cygpath' command can now convert arbitrary windows and unix
paths into the short ms-dos 8.3 equivalents. This tools might allow the
windows build system to better deal with those messy long Windows file and
directory names that contain spaces.
EG:
warneg@GRDGROL99X1028: src [1]$ pwd
/cygdrive/c/Documents and Settings/WarnesGR/My
Documents/cygwin_home/src/gregmisc/src
2002 Jan 28
4
Type III Sums of Squares
I am trying to reproduce an analysis done in SAS from which Type III Sums of
squares are used. How can you get Type III sums of squares in an aov similar
to what SAS provides?
With best wishes and kind regards I am
Sincerely,
Corey A. Moffet
Instructor
Department of Range, Wildlife, and Fisheries Management
Mail Stop 2125
Texas Tech University
Lubbock, Texas 79409-2125
(806) 742-2843 Voice
2002 Apr 29
2
Lotos 1-2-3 date to POSIXct
I have some data that was created for import into a Lotus 1-2-3 spreadsheet
and on of the columns is time. The
time is akin to Julian were the value 1 is mapped "01-Jan-00 12:00:00 AM" in
Lotus 1-2-3. Is there a function in an R package that can convert this
numeric vector to a POSIXct vector?
With best wishes and kind regards I am
Sincerely,
Corey A. Moffet
Instructor
Department
2008 Apr 16
2
Post hoc tests with lme
Using the "ergoStool" data cited in Mixed-Effects Models in S and
S-PLUS by Pinheiro and Bates as an example, we have
========
> library(nlme)
> fm <- lme(effort~Type-1, data=ergoStool, random=~1|Subject)
> summary(fm)
Linear mixed-effects model fit by REML
Data: ergoStool
AIC BIC logLik
133.1308 141.9252 -60.5654
Random effects:
Formula: ~1 | Subject
2002 Apr 17
4
Problem w/ axis and distortion in a plotting function
I have a function for plotting soil texture that I am having a problem with.
The function is:
plot.psd <- function(sand, clay, ...) {
conv.ter <- function(x, y) {
x.con <- 100 - x - y*cos(1/3*pi)
y.con <- y*sin(1/3*pi)
data.frame(x=x.con, y=y.con)
}
plot(conv.ter(sand, clay), xlim = c(0,100), ylim = c(0,100*sin(1/3*pi)),
axes = FALSE, xlab="",
2002 Sep 13
1
Contrasts in ANOVA table
Hello All,
Is there a way of producing an ANOVA table split into contrasts, thus showing the contrasts sums of squares and associated p-values?
Thanks,
Martin.
Martin Hoyle,
School of Life and Environmental Sciences,
University of Nottingham,
University Park,
Nottingham,
NG7 2RD,
UK
Webpage: http://myprofile.cos.com/martinhoyle
2003 Jan 21
1
Modified F-test for heterogeneous error variances
Dear R-help:
Does anyone know of a package in R that will do Welch's modified F-test
for heterogeneous error variances? Are there other statistical techniques
available in R that test the equality of means when homoscedastisity
is violated? 't.test' does this in the pairwise sense when var.equal =
TRUE.
With best wishes and kind regards I am
Sincerely,
Corey A. Moffet
Support
2003 Dec 02
1
Is there a way to use CGIwithR in Windows?
Dear R-Help,
Does anyone know of a way to use CGIwithR in Windows? David Firth the
author of CGIwithR states "It ought to be possible to adapt it for use also
in conjunction with web servers running under Windows NT ... but the author
has no plans for that." I have developed some applications in R that I would
like to make available through a web interface using CGIwithR but at this
2002 Aug 20
1
override ask = TRUE in plot.formula
I am having difficulty with plot.formula.
For example:
-------------------
dat <- data.frame(y = c(1,1,1,2,2,2,3,3,3,4,4,4),
x1 = as.ordered(c(1,1,1,1,1,1,2,2,2,2,2,2)),
x2 = as.ordered(c(1,1,1,2,2,2,1,1,1,2,2,2)))
plot(y ~ x1 + x2, data = dat) # Works fine "interactively" asking:
# "Hit <Return> to see next plot:"
#
2006 Jul 18
3
Test for equality of coefficients in multivariate multiple regression
Hello,
suppose I have a multivariate multiple regression model such as the
following:
> DF<-data.frame(x1=rep(c(0,1),each=50),x2=rep(c(0,1),50))
> tmp<-rnorm(100)
> DF$y1<-tmp+DF$x1*.5+DF$x2*.3+rnorm(100,0,.5)
> DF$y2<-tmp+DF$x1*.5+DF$x2*.7+rnorm(100,0,.5)
> x.mlm<-lm(cbind(y1,y2)~x1+x2,data=DF)
> coef(x.mlm)
y1 y2
(Intercept)
2002 Nov 19
5
help reading a variably formatted text file
Dear R-Help,
I have a generated file that looks like the following:
----- Begin file -----
#
# Output File
#
float Version 2002.700000000000
int Numdays 31
int NumOFEs 1
#
# Hillslope-specific variables
#
char HillVarNames[ 3 ]
{Days In Simulation}
{Hillslope: Precipitation (mm)}
2008 Mar 25
1
Subset of matrix
Dear R users
I have a big matrix like
6021 1188 790 290 1174 1015 1990 6613 6288
100714
6021 1 0.658 0.688 0.474 0.262 0.163 0.137 0.32
0.252 0.206
1188 0.658 1 0.917 0.245 0.331 0.122 0.148 0.194
0.168 0.171
790 0.688 0.917 1 0.243 0.31 0.122 0.15 0.19
0.171 0.174
290 0.474
2003 Feb 15
1
tests for spericity
Dear R-help,
Does any one know of a function/package in R that will test the assumption of
spericity in a split-plot analysis of variance? How are people dealing with
this issue in R?
With best wishes and kind regards I am
Sincerely,
Corey A. Moffet
Support Scientist
University of Idaho
Northwest Watershed Research Center
800 Park Blvd, Plaza IV, Suite 105
Boise, ID 83712-7716
(208) 422-0718
2004 Apr 29
1
model.tabels warning refers to wrong function (PR#6839)
Full_Name: Corey A. Moffet
Version: 1.8.1
OS: Windows 2000 and RHL 9
Submission from: (NULL) (199.133.140.156)
The function model.tables.aov and perhaps other model.tables methods refer the
user to use the function se.contrasts when the design is unbalanced. The
function name is se.contrast (singular).
2001 Oct 02
4
plot of Bernoulli data
I have some Bernoulli data something like this:
x<-sort(runif(100,1,20))
p<-pnorm(x,10,3)
y<-as.numeric(runif(x)<p)
plot(x,y)
lines(x,p)
This plot is not very satisfactory because the ogive does not visually
fit the (0,1) points very well, and also because the points tend to fall
on top of one another. The second problem can be eliminated by adding
vertical jitter. However I was
2003 Oct 13
1
extracting quoted text from character string
Hello all,
I am trying to solve a problem, and my solution is rather ugly and not very
general. The posts for "[R] help with gsub and grep functions" seemed
relevent
and gave me hope for a more refined and more general solution.
The Problem:
line <- "'this text has spaces' 'thisNot' 3 4 5 6 7 8 9 10"
bad.line <- "'this text has spaces'
2003 Feb 13
3
search contrasts tutorial
I'm looking for a tutorial or notes on the use of contrasts factor in
linear model in R,
I've found some mails and infos about in various documents about R,
but I've probably missed
a good review on this subject.
--
Robert Espesser
Laboratoire Parole et Langage UMR 6057, CNRS
29 Av. Robert Schuman 13621 AIX (FRANCE)
Tel: +33 (0)4 42 95 36 26 Fax: +33 (0)4 42 59 50
2004 Jun 28
1
unbalanced design for anova with low number of replicates
Hello,
I'm wondering what's the best way to analyse an unbalanced design with a low number of replicates. I'm not a statistician, and I'm looking for some direction for this problem.
I've a 2 factor design:
Factor batch with 3 levels, and factor dose within each batch with 5 levels. Dose level 1 in batch one is replicated 4 times, level 3 is replicated only 2 times. all
2003 May 07
2
Plot labeling question
I have an older Splus script that generated some
regression graphics for me. In it, I used the commands
key(10,800,text="<blah1>",border=0)
key(10,750,text="<blah2>", border=0, background = 9)
text(locator(1),"95% Confidence Limits")
locator(n=2,type="l")
text(locator(1),"Model for Group 1")
locator(n=2,type="l")
There is