Displaying 20 results from an estimated 700 matches similar to: "linear mixed-effects models with two random variables?"
2012 Sep 11
0
how to perform multiple comparisons with anova.glm significant interactions?
Dear R users
I want to evaluate my significant interactions among 3 predictors in glm
(one is a factor and 2 are numeric indices).
I had a 3rd order interaction in my anova.glm and I'm wondering how to
investigate them. I read multcomp package but I found it difficult for me.
#Say e.g. (I'm not using real values and in this e.g. does not have the
interactions I'm saying - but my data
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)
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
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
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,
2009 Apr 01
3
How to prevent inclusion of intercept in lme with interaction
Dear friends of lme,
After so many year with lme, I feel ashamed that I cannot get this to work.
Maybe it's a syntax problem, but possibly a lack of understanding.
We have growth curves of new dental bone that can well be modeled by a
linear growth curve, for two different treatments and several subjects as
random parameter. By definition, newbone is zero at t=0, so I tried to force
the
2008 Feb 21
1
update don't find an object
Hi,
I have a situation here.
I try this update:
mmaa <- update(mma,biomass~qvartemp)
but I have this message:
Error in eval(expr, envir, enclos) : object "qvartemp" not found
but this object exist:
[1] "cont" "i" "levelsord" "mma" "qvar" "qvarmma"
[7] "qvartemp" "test"
2010 Sep 16
1
Help for an absolutely r-noob
Hello together,
I am an absolute noob in R and therefore I need help urgently. I have
received a script from my tutor with plot functions in it. However, I can'
manage to adapt these plots.
The hole script is as follows:
setwd("E:/")
##### (1) Read data ###
dat <- read.table("Komfort_Tatsaechliche_ID_Versuchsreihe_1.txt",
header=TRUE,
sep="\t",
2017 Jun 21
0
Help/ Mathematics
Hi Ahmed,
Your problem appears trivial as you have already specified the form of
the calculation.
Learn how to "extract" specified elements from a data structure:
# first value
sum(dataset1$NPP[dataset1$date >= date1 &
dataset1$date <= date2])
# second value
dataset2$biomass[dataset2$date == date2] -
dataset2$biomass[dataset2$date == date1]
# third value
2003 Apr 08
2
Basic LME
Hello R Users,
I am investigating the basic use of the LME function, using the following example;
Response is Weight, covariate is Age, random factor is Genotype
model.lme <- lme (Weight~Age, random=~ 1|Genotype)
After summary(model.lme), I find that the estimate of Age is 0.098 with p=0.758.
I am comparing the above model with the AOV function;
model.aov <- aov (Weight~Age + Genotype)
2011 Apr 20
3
succession time series graph
Dear gracious R community,
I would like to produce charts of phytoplankton biomass changes
through time. Each species has a line, and the biomass varies in
mirror form along the line for each species along the X time axis.
Here is an example of what I'd like to do:
http://www.er.uqam.ca/nobel/r30240/Succession.jpg
Any suggestions?
Thanks
David Bird
UQAM, Montreal
2009 Jul 23
1
simple lme question
Hi everyone,
I am trying to analyse my data from a small plant experiment (for a meeting tomorrow afternoon) and am a beginner to R so I apologise if this is a very basic question.
I carried out a plant experiment examining plant interactions between two species (A and B) under different watering treatments. I had:
- 7 watering treatments (7 different watering frequencies labelled 1-7)
- 3
2004 Jan 05
3
Heeeeeelp! Estimatet Marginal Means of ANOVA needed!
Hello!
I urgently need to know if it is possible (and if so, how to do) to get
the "Estimatet marginal means" from an ANOVA.
Or explained more coplicated: It's about plants sewn in 2 densities & 2
patterns. The Variable is biomass and I also use a Covariate. There are highly
significant differences between density & pattern but I don't know which of the
2 densities
2017 Jun 21
4
Help/ Mathematics
Hi R users,
I need your help to write a code in r that does the following
calculation from three different datasets;
ac = 1/sum (NPP from date 1 to date 2, dataset=1) * (biomass at date 2
-biomass at date 1, dataset = 2) + (littfall at date 2, dataset=3).
all the dates are in yr-month-day format. Which library or function
Should I use to tell R do these calculations of these variables at
2013 Mar 26
2
Problem with nested for-loop
Hello,
I'm working on a problem using nested for-loops and I don't know if it's a
problem with the order of the loops or something within the loop so any
help with the problem would be appreciated. To briefly set up the problem.
I have 259 trees (from 11 different species, of unequal count for each
species) of which I am trying to predict biomass. For each tree species I
have 10000
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
2011 Sep 27
1
ANOVA define as factor or not
Hi all
This is probably a simple problem but somehow I am having much trouble with
finding a solution, so I seek your help!
I have a data-set with continuous response variables. The explanatory
variably is 4xpH treatments (so 8.08, 7.94, 7.81 and 7.71) so also
continuous and not technically factorial.
However I have decided to do Anova's (as well as regression) to explore the
effect of
2007 May 24
4
Function to Sort and test AIC for mixed model lme?
Hi List
I'm running a series of mixed models using lme, and I wonder if there
is a way to sort them by AIC prior to testing using anova
(lme1,lme2,lme3,....lme7) other than by hand.
My current output looks like this.
anova
(lme.T97NULL.ml,lme.T97FULL.ml,lme.T97NOINT.ml,lme.T972way.ml,lme.T97fc.
ml, lme.T97ns.ml, lme.T97min.ml)
Model df AIC BIC logLik
2017 Jun 30
3
Predict
Sorry for the confusion, here is the edited question.
The data= Stand_Height (attached) is recorded from 12/1/2009 to
12/31/2015 (25 observations) and the other dataset (leafbiom) is
recorded from 10/7/2009 to 12/29/2016 (daily observations).
I want to use the 25 observations of stand height to predict the daily
stand height from 10/7/2009 to 12/29/2016. The daily stand height will
be multiplied