Displaying 20 results from an estimated 500 matches similar to: "Significance of slopes"
2010 Jan 07
2
Extract p-value from linear model
Dear all,
I have the following question.
Is it possible in R to call for the p-value directly in a model like this
a <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
b <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
summary(lm(a~(b+0)))
or even in this
a <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
b <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
2007 Oct 29
1
biserial correlation with pkg polycor
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2001 May 23
2
help: exponential fit?
Hi there,
I'm quite new to R (and statistics),
and I like it (both)!
But I'm a bit lost in all these packages,
so could someone please give me a hint
whether there exists a package for fitting
exponential curves (of the type
t --> \sum_i a_i \exp( - b_i t))
on a noisy signal?
In fact monoexponential decay + polynomial growth
is what I'd like to try.
Thanks in advance,
2005 Aug 30
1
Convert ftable to latex?
Dear list,
I cannot make the latex command to output a ftable objet the way I
want it. Is it posible?
I found a post in the archives saying that one should use the rgroup
and n.rgroup arguments to supply the row names, but so far I have been
unsuccessful.
This is what I have:
>
2006 Dec 01
3
error in hetcor function (polycor package)?
I have been using the hetcor function in the polycor package. When I
don't specify the use option everything runs smoothly. However, when I
specify use either as "pairwise.complete.obs" or "complete.obs" I get
this error
Error in optim(rho, f, control = control, hessian = TRUE, method =
"BFGS") :
non-finite value supplied by optim
Is this an error in
2011 May 03
3
ANOVA 1 too few degrees of freedom
I'm running an ANOVA on some data for respiration in a forest. I am having a
problem with my degrees of freedom. For one of my variables I get one fewer
degrees of freedom than I should.
I have 12 plots and I therefore expected 11 degrees of freedom, but instead
I got 10.
Any ideas?
I have some code and output below:
> class(Combined.Plot)
[1] "character"
>
2011 Mar 07
5
Parsing question, partly comma separated partly underscore separated string
Dear R-list,
I have a partly comma separated partly underscore separated string that I am trying to parse into R.
Furthermore I have a bunch of them, and they are quite long. I have now spent most of my Sunday trying to figure this out and thought I would try the list to see if someone here would be able to get me started.
My data structure looks like this,
(in a example.txt file)
Subject
2006 Aug 24
1
how to constrast with factorial experiment
Hello, R users,
I have two factors (treat, section) anova design experiment where
there are 3 replicates. The objective of the experiment is to test if
there is significant difference of yield between top (section 9 to 11)
and bottom (section 9 to 11) of the fruit tree under treatment. I
found that there are interaction between two factors. I wonder if I
can contrast means from levels of
2010 Dec 01
2
Lattice dotplots
Dear,
I have a dataset with 4 subjects (see ID in example), and 4 treatment (see
TRT in example) which are tested on 2 locations and in 3 blocs. By using
Lattice dotplot, I made a graph that shows the raw data per location and
per bloc. In that graph, I would like to have a reference line per bloc
that refers to the first treatment (T1). However, I can not find how to do
that.
I can make
2007 Mar 14
1
How to transform matrices to ANOVA input datasets?
Hello, R experts,
I have a list called dataHP which has 30 elements (m1, m2, ..., m30).
Each element is a 7x6 matrix holding yield data from two factors
experimental design, with treatment in column, position in row. For
instance, the element 20 is:
dataHP[[20]]
col1 col2 col3 trt1 trt2 trt3
[1,] 22.0 20.3 29.7 63.3 78.5 76.4
[2,]
2006 Mar 03
1
Help with lme and correlated residuals
Dear R - Users
I have some problems fitting a linear mixed effects model using the lme function (nlme library). A sample data is as shown at the bottom of this mail. I fit my linear mixed model
using the following R code:
bmr <-lme (outcome~ -1 + as.factor(endpoint)+ as.factor(endpoint):trt, data=datt,
random=~-1 + as.factor(endpoint) + as.factor(endpoint):trt|as.factor(Trial),
2008 Oct 15
2
Network meta-analysis, varConstPower in nlme
Dear Thomas Lumley, and R-help list members,
I have read your article "Network meta-analysis for indirect treatment
comparisons" (Statist Med, 2002) with great interest. I found it very
helpful that you included the R code to replicate your analysis;
however, I have had a problem replicating your example and wondered if
you are able to give me a hint. When I use the code from the
2013 Sep 13
1
Creating dummy vars with contrasts - why does the returned identity matrix contain all levels (and not n-1 levels) ?
Hello,
I have a problem with creating an identity matrix for glmnet by using the
contrasts function.
I have a factor with 4 levels.
When I create dummy variables I think there should be n-1 variables (in this
case 3) - so that the contrasts would be against the baseline level.
This is also what is written in the help file for 'contrasts'.
The problem is that the function
2008 Jun 04
1
"& not meaningful for factors"
I am trying to define groupings from levels of factor variables and this the warning message that R give
"& not meaningful for factors".
The nature of my task is this. I have a variable stage which has the levels (1B, 2A, 2B) - these are the AJCC TNM stages of cancer, and another variable diameter with factor levels ("=< 4", "4 - 6.5, > 6.5; limit values are
2012 Jan 27
1
Confused with Student's sleep data description
I am confused whether Student's sleep data "show the effect of two
soporific drugs" or Control against Treatment (one drug). The reason
is the next:
> require(stats)
> data(sleep)
> attach(sleep)
> extra[group==1]
numeric(0)
> group
[1] Ctl Ctl Ctl Ctl Ctl Ctl Ctl Ctl Ctl Ctl Trt Trt Trt Trt Trt Trt Trt Trt Trt
[20] Trt
Levels: Ctl Trt
> sleep$group
[1] 1 1 1 1 1
2011 Dec 11
2
multiple comparison of interaction of ANCOVA
Hi there,
The following data is obtained from a long-term experiments.
> mydata <- read.table(textConnection("
+ y year Trt
+ 9.37 1993 A
+ 8.21 1995 A
+ 8.11 1999 A
+ 7.22 2007 A
+ 7.81 2010 A
+ 10.85 1993 B
+ 12.83 1995 B
+ 13.21 1999 B
+ 13.70 2007 B
+ 15.15 2010 B
+ 5.69 1993 C
+ 5.76 1995 C
+ 6.39 1999
2009 Jun 27
4
questions about meta-analysis
Dear R users:
In the example of meta-analysis (cochrane, package rmeta), I can not found the p-value of Test for overall effect, and some other indices (Z, I, weight and et al). How can I get the these indices listed?
> library(rmeta)
> data(cochrane)
> cochrane
name ev.trt n.trt ev.ctrl n.ctrl
1 Auckland 36 532 60 538
2 Block 1 69 5
2007 Jun 01
2
Interaction term in lmer
Dear R users,
I'm pretty new on using lmer package. My response is binary and I have fixed
treatment effect (2 treatments) and random center effect (7 centers). I want
to test the effect of treatment by fitting 2 models:
Model 1: center effect (random) only
Model 2: trt (fixed) + center (random) + trt*center interaction.
Then, I want to compare these 2 models with Likelihood Ratio Test.
2008 Mar 05
1
Question on "assign(paste.."
Hello,
I'm having trouble in using "assign(paste ..." command . I could create
several dataframes following trinomial distribution using it but it could
not be used to check their row means of the created dataframe.
For example, the following works:
probTrt=matrix(0,4,3);
probTrt;
#malf, death, normal
probTrt[1,]=c(0.064,0.119,0.817);#for Trt 1
probTrt[2,]=c(0.053,0.125,0.823);#for
2011 Apr 20
2
survexp with weights
Hello,
I probably have a syntax error in trying to generate an expected
survival curve from a weighted cox model, but I can't see it. I used
the help sample code to generate a weighted model, with the addition
of a "weights=albumin" argument (I only chose albumin because it had
no missing values, not because of any real relevance). Below are my
code with the resulting error