Displaying 20 results from an estimated 1000 matches similar to: "SE for combined data"
2001 Dec 05
3
Histograms per coding variable
Dear all
I have a dataset that looks like:
fr.wt site
1 4400 glen
2 235 glen
3 225 glen
' ' '
' ' '
' ' '
82 550 glen
83 550 kom
84 550 kom
' ' '
' ' '
' ' '
191 820 kom
192 2000 soet
' ' '
' ' '
I need to do a series of histograms for each of the codes, levels or
factors in
2003 Jan 30
1
Kruskal-Wallis, Friedman tests and Tukey HSD
Dear all
Is there any way of doing a Tukey HSD post-hoc test after a Kruskal-
Wallis or Friedman rank sum test (in the ctest package)?
Thanks in advance,
Albertus
Dr. Albertus J. Smit
Department of Botany
University of Cape Town
Private Bag Rondebosch
7700
South Africa
Tel. +27 21 689 3032
2002 Sep 25
2
Re-ordering the order of lattice graphics panels
Dear all
I have made some lattice graphs (bwplot(dead ~ treat | group,...).
'group' is a factor with three levels (Artemia larvae, Abalone larvae
and Abalone spat), and the result is a graph with three panels
corresponding to the levels in 'group', ordered in alphabetical order
from bottom to top, as expected.
How does one re-order the order in which the levels of
2011 Aug 24
1
R (&stats) newcomer.... help!
Hi all,
I hope that i've posted this in the correct place. if not, please accept my
apologies (where should this go?)
I have carried out experimental removal of bivalves at 2 intertidal shores.
Bivalves were removed by raking of surface sediments. I wish compare the
biomass values of for a total of 8 species between the 2 shores
My 3 treatments are: Undisturbed Controls (Cont), Procedural
2003 Nov 06
1
Levelplot and NAs
Dear all
How does one get a levelplot (lattice library) to plot NAs in a
different colour to that specified in the default colorkey?
Thanks in advance,
Albertus
--
Dr. Albertus J. Smit
Department of Botany
University of Cape Town
PO Box Rondebosch
7700
SOUTH AFRICA
-------------------------------------------------
This mail sent through IMP: http://horde.org/imp/
2002 Jul 16
3
dose.p in MASS
Dear all
I need to obtain an estimate of the 50% lethal dose (LD50) from a
logistic regression model obtained by applying the glm procedure to
some binomial data. The model appears to fit the data very well. I
used dope.p from MASS to try and find LD50.
The following output appears:
> dose.p(iso.glm.logit, cf = c(1,3), p = 1:3/4)
Error in dose.p(iso.glm.logit, cf = c(1, 3), p = 1:3/4) :
2002 Oct 31
0
ANOVAs per grouping variable
Dear all
I have a question regarding repeating a series of nested ANOVAs.
The model is:
fit <- aov(response ~ treatment + plot/rep)
Treatment has three levels, there are three plots and each plot has
four replicates. Now, the experiment was also repeated six times
during the year. Ideally I would have liked to include sampling time
(month) as an additional factor in the analysis, but
2002 Jul 23
0
Comparing slopes of several linear models
Dear all
I have the following data (a shortened extract
shown; some replictates of time deleted) to which I
fitted the linear model given below:
time group mass
11 control 0.019
11 control 0.014
14 control 0.0306
14 control 0.0289
14 control 0.0236
17 control 0.0469
17 control 0.0709
11 five 0.0077
11 five
2004 Oct 25
2
aov documentation page: question
Dear all
I was looking at the aov documentation page and came across the
following which seems like a contradiction to me:
" This provides a wrapper to |lm| for fitting linear models to balanced
or unbalanced experimental designs." (I presume 'This' refers to aov)
and
"|aov| is designed for balanced designs, and the results can be hard to
interpret without
2005 Nov 10
2
IF/Else
Hi,
I am trying to write a for loop with if else statements to calculate
biomass density estimates for different types of sampling gear.
My code is:
bmd=for (i in 1:length(Gear)){
if (Gear==20) {bioden=Biomass/141}
else {if (Gear==23) {bioden=Biomass/68}}
else {if (Gear==160) {bioden=Biomass/4120}}
else {if (Gear==170) {bioden=Biomass/2210}}
else {if (Gear==300)
2011 Feb 06
1
anova() interpretation and error message
Hi there,
I have a data frame as listed below:
> Ca.P.Biomass.A
P Biomass
1 334.5567 0.2870000
2 737.5400 0.5713333
3 894.5300 0.6393333
4 782.3800 0.5836667
5 857.5900 0.6003333
6 829.2700 0.5883333
I have fit the data using logistic, Michaelis?Menten, and linear model,
they all give significance.
> fm1 <- nls(Biomass~SSlogis(P, phi1, phi2, phi3), data=Ca.P.Biomass.A)
2000 Aug 12
1
Nonlinear regression question
Dear R users
I recently migrated from Statistica/SigmaPlot (Windows) to R (Linux), so
please excuse if this may sound 'basic'.
When running a nonlinear regression (V = Vmax * conc / (Ks + conc), i.e.
Michaelis-Menten) on SigmaPlot, I get the output listed below:
>>>Begin SigmaPlot Output<<<
R = 0.94860969 Rsqr = 0.89986035 Adj Rsqr = 0.89458984
Standard Error of
2011 Jul 14
1
LME and overall treatment effects
Hello fellow R users,
I am having a problem finding the estimates for some overall treatment
effects for my mixed models using 'lme' (package nlme). I hope someone
can help.
Firstly then, the model:
The data: Plant biomass (log transformed)
Fixed Factors: Treatment(x3 Dry, Wet, Control) Year(x8 2002-2009)
Random Factors: 5 plots per treatment, 5 quadrats per plot (N=594 (3*5*5*8)
2012 Feb 03
1
ordering of factor levels in regression changes result
I was surprised to find that just changing the base level of a factor variable changed the number of significant coefficients in the solution.
I was surprised at this and want to know how I should choose the order of the factors, if the order affects the result.
Here is the small example. It is taken from 'The R Book', Crawley p. 365.
The data is at
2017 Jul 06
0
Bayes Factor
Hello R Community,
Subject: Bayes Factor
A Bayesian ANOVA of the form:
competitionBayesOut <- anovaBF(biomass ~ clipping, data = competition)
Returns the following Error message:
Error in (function (classes, fdef, mtable) :
unable to find an inherited method for function ?compare? for
signature ?"BFlinearModel", "missing", "tbl_df"?
My guess the problem is in
2012 Sep 14
1
linear mixed-effects models with two random variables?
Dear R users,
Does anyone knows how to run a glmm with one fixed factor and 2 random
numeric variables (indices)? Is there any way to force in the model a
separate interaction of those random variables with the fixed one?
I hope you can help me.
#eg.
Reserve <- rep(c("In","Out"), 100)
fReserve <- factor(Reserve)
DivBoulders <- rep
2013 Nov 07
1
problem with interaction in lmer even after creating an "interaction variable"
Dear all,
I have a problem with interactions in lmer. I have 2 factors (garden and
gebiet) which interact, plus one other variable (home), dataframe arr. When
I put:
/
lmer (biomass ~ home + garden:gebiet + ( 1|Block), data = arr)/
it writes:
/Error in lme4::lFormula(formula = biomass ~ home + garden:gebiet + (1 | :
rank of X = 28 < ncol(X) = 30/
In the lmer help I found out that if not
2011 Apr 13
1
print to .jpeg
Evening folks,
I'm trying to print a series of graphs to .jpeg using a variable as the
title, but run into the difficultly that I can't find a way to append the
file extension to the .jpeg (in this case extensionless!) files.
Example:
----
species.name="CussoniaHolstii"
dia<-10:100
biomass = -21.4863 + 0.5797 * (dia ^ 2)
biomass
jpeg(species.name)
plot (biomass,
2010 Sep 16
0
problems trying to reproduce structural equation model using the sem package
Hello,
I've been unsuccessfully trying to reproduce a sem from Grace et al.
(2010) published in Ecological Monographs:
http://www.esajournals.org/doi/pdf/10.1890/09-0464.1
The model in question is presented in Figure 8, page 81. The errors
that I've been getting are:
1. Using a correlation matrix:
res.grace <- sem(grace.model, S = grace, N = 190)
Warning message:
In sem.default(ram
2006 May 18
4
Nested design
Dear list members,
I'd like to perform a glm analysis with a hierarchically nested design. In
particular,
I have one fixed factor ("Land Use Classes") with three levels and a random
factor ("quadrat") nested within Land Use Classes with different levels per
classes (class artificial = 1 quadrat; class crops = 67 quadrats; and class
seminatural = 30 quadrats).
I have four