95% CI of A,C,E estimates in Twin model
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Sabha
Joined: 05/18/2010
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Can anyone help me with the function or syntex needed to calculate the 95% CI for A,C,E estimates in the existing
UnivariateTwinAnalysis_MatrixRaw.R script.
UnivariateTwinAnalysis_MatrixRaw.R script.
Thanks in advance.
See this part of the wiki:
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In reply to See this part of the wiki: by neale
Thanks for your help. I was
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In reply to Thanks for your help. I was by Sabha
Same way, just use the names
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In reply to Same way, just use the names by neale
Error in free[i, j] : subscript out of bounds
Can you please check what might be wrong with how I adjusted the UnivariateTwinAnalysis_PathRaw.R code (see below)? Or might there be a bug in the software version I'm running? Thanks!
---
# Load Data
data(twinData)
# Select Variables for Analysis
selVars <- c('bmi1','bmi2')
aceVars <- c("A1","C1","E1","A2","C2","E2")
# Select Data for Analysis
mzData <- subset(twinData, zyg==1, selVars)
dzData <- subset(twinData, zyg==3, selVars)
# Generate Descriptive Statistics
colMeans(mzData,na.rm=TRUE)
colMeans(dzData,na.rm=TRUE)
cov(mzData,use="complete")
cov(dzData,use="complete")
require(OpenMx)
# Path objects for Multiple Groups
manifestVars=selVars
latentVars=aceVars
# variances of latent variables
latVariances <- mxPath( from=aceVars, arrows=2,
+ free=FALSE, values=1 )
# means of latent variables
latMeans <- mxPath( from="one", to=aceVars, arrows=1,
+ free=FALSE, values=0 )
# means of observed variables
obsMeans <- mxPath( from="one", to=selVars, arrows=1,
+ free=TRUE, values=20, labels="mean" )
# path coefficients for twin 1
pathAceT1 <- mxPath( from=c("A1","C1","E1"), to="bmi1", arrows=1,
+ free=TRUE, values=.5, label=c("a","c","e") )
# path coefficients for twin 2
pathAceT2 <- mxPath( from=c("A2","C2","E2"), to="bmi2", arrows=1,
+ free=TRUE, values=.5, label=c("a","c","e") )
# covariance between C1 & C2
covC1C2 <- mxPath( from="C1", to="C2", arrows=2,
+ free=FALSE, values=1 )
# covariance between A1 & A2 in MZ twins
covA1A2_MZ <- mxPath( from="A1", to="A2", arrows=2,
+ free=FALSE, values=1 )
# covariance between A1 & A2 in DZ twins
covA1A2_DZ <- mxPath( from="A1", to="A2", arrows=2,
+ free=FALSE, values=.5 )
# Data objects for Multiple Groups
dataMZ <- mxData( observed=mzData, type="raw" )
dataDZ <- mxData( observed=dzData, type="raw" )
# Combine Groups
paths <- list( latVariances, latMeans, obsMeans,
+ pathAceT1, pathAceT2, covC1C2 )
mxMatrix(type="Full",nrow=3,ncol=1,free=T,values=.6,labels=c("a","c","e"),name="ace")
mxAlgebra( (ace%^%2) %x% solve(t(ace)%*%ace), name="StdVarComp",dimnames=list(c("a2","c2","e2"),NULL) )
mxCI("StdVarComp")
modelMZ <- mxModel(model="MZ", type="RAM", manifestVars=selVars,
+ latentVars=aceVars, paths, covA1A2_MZ, dataMZ, mxCI("StdVarComp"))
modelDZ <- mxModel(model="DZ", type="RAM", manifestVars=selVars,
+ latentVars=aceVars, paths, covA1A2_DZ, dataDZ )
minus2ll <- mxAlgebra( expression=MZ.fitfunction + DZ.fitfunction,
+ name="minus2loglikelihood" )
obj <- mxFitFunctionAlgebra( "minus2loglikelihood" )
modelACE <- mxModel(model="ACE", modelMZ, modelDZ, minus2ll, obj )
# Run Model
fitACE <- mxRun(modelACE, intervals=TRUE)
Error in free[i, j] : subscript out of bounds
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In reply to Error in free[i, j] : subscript out of bounds by olleee
Error message has been improved
> fitACE <- mxRun(modelACE, intervals=TRUE)
Error: Unknown reference to 'StdVarComp' detected in a confidence interval specification in model 'ACE'
You should check spelling (case-sensitive), and also addressing the right model: to refer to an algebra
See help(mxCI) to see how to refer to an algebra in a submodel.
FYI, I got as far as: runHelper(model, frontendStart, intervals, silent, suppressWarnings, unsafe, checkpoint, useSocket, onlyFrontend, useOptimizer)
This clue was enough for me to figure out that some of the objects were missing from your model. Specifically, because the lines
mxMatrix(type="Full",nrow=3,ncol=1,free=T,values=.6,labels=c("a","c","e"),name="ace")
mxAlgebra( (ace%^%2) %x% solve(t(ace)%*%ace), name="StdVarComp",dimnames=list(c("a2","c2","e2"),NULL) )
mxCI("StdVarComp")
were not within the parentheses of an mxModel() function call, it could not find the objects to which the mxCI() referred. I modified the code to put the results of these commands into suitably named objects, and included these objects in the subsequent mxModel() call.
library(OpenMx)
# Load Data
data(twinData)
# Select Variables for Analysis
selVars <- c('bmi1','bmi2')
aceVars <- c("A1","C1","E1","A2","C2","E2")
# Select Data for Analysis
mzData <- subset(twinData, zyg==1, selVars)
dzData <- subset(twinData, zyg==3, selVars)
# Generate Descriptive Statistics
colMeans(mzData,na.rm=TRUE)
colMeans(dzData,na.rm=TRUE)
cov(mzData,use="complete")
cov(dzData,use="complete")
require(OpenMx)
# Path objects for Multiple Groups
manifestVars=selVars
latentVars=aceVars
# variances of latent variables
latVariances <- mxPath( from=aceVars, arrows=2,
free=FALSE, values=1 )
# means of latent variables
latMeans <- mxPath( from="one", to=aceVars, arrows=1,
free=FALSE, values=0 )
# means of observed variables
obsMeans <- mxPath( from="one", to=selVars, arrows=1,
free=TRUE, values=20, labels="mean" )
# path coefficients for twin 1
pathAceT1 <- mxPath( from=c("A1","C1","E1"), to="bmi1", arrows=1,
free=TRUE, values=.5, label=c("a","c","e") )
# path coefficients for twin 2
pathAceT2 <- mxPath( from=c("A2","C2","E2"), to="bmi2", arrows=1,
free=TRUE, values=.5, label=c("a","c","e") )
# covariance between C1 & C2
covC1C2 <- mxPath( from="C1", to="C2", arrows=2,
free=FALSE, values=1 )
# covariance between A1 & A2 in MZ twins
covA1A2_MZ <- mxPath( from="A1", to="A2", arrows=2,
free=FALSE, values=1 )
# covariance between A1 & A2 in DZ twins
covA1A2_DZ <- mxPath( from="A1", to="A2", arrows=2,
free=FALSE, values=.5 )
# Data objects for Multiple Groups
dataMZ <- mxData( observed=mzData, type="raw" )
dataDZ <- mxData( observed=dzData, type="raw" )
# Combine Groups
paths <- list( latVariances, latMeans, obsMeans,
pathAceT1, pathAceT2, covC1C2 )
aceMat <- mxMatrix(type="Full",nrow=3,ncol=1,free=T,values=.5,labels=c("a","c","e"),name="ace")
StdVarCompAlg <- mxAlgebra( (ace%^%2) %x% solve(t(ace)%*%ace), name="StdVarComp", dimnames=list(c("a2","c2","e2"),NULL) )
mxCI("StdVarComp")
modelMZ <- mxModel(model="MZ", type="RAM", manifestVars=selVars,
latentVars=aceVars, paths, covA1A2_MZ, dataMZ )
modelDZ <- mxModel(model="DZ", type="RAM", manifestVars=selVars,
latentVars=aceVars, paths, covA1A2_DZ, dataDZ )
minus2ll <- mxAlgebra( expression=MZ.fitfunction + DZ.fitfunction,
name="minus2loglikelihood" )
obj <- mxFitFunctionAlgebra( "minus2loglikelihood" )
modelACE <- mxModel(model="ACE", modelMZ, modelDZ, minus2ll, obj, aceMat, StdVarCompAlg, mxCI("StdVarComp"))
# Run Model
summary(fitACE <- mxRun(modelACE, intervals=TRUE))
The lower CI on the estimate of C which is already at zero sort of flunks out but could be considered to be zero.
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In reply to Error message has been improved by AdminNeale
ran into the same problem
I know this is an old thread, but I ran into the same problem and would like to ask for your help.
I have been trying to adjust this code to mine, in order to get the CI of the ACE standardized variance components (a2/V etc..).
This is what I added:
#Confidence interval for the variance components
aceMat <-mxMatrix(type="Full",nrow=3,ncol=1,free=T,values=StartVar.ACE,labels=c("a","c","e"),name="ace")
mxal <-mxAlgebra( (ace%^%2) %x% solve(t(ace)%*%ace), name="StdVarComp",dimnames=list(c("a2","c2","e2"),NULL) )
mxCI("StdVarComp")
obj <- mxFitFunctionMultigroup(c("MZM","DZM","MZF","DZF"))
modelACE.Homog <- mxModel(model="ACE_Homog",modelMZM, modelDZM,modelMZF, modelDZF, obj, aceMat,mxal, mxCI("StdVarComp") )
mxAutoStart(modelACE.Homog)
fitACE.Homog <- mxTryHardOrdinal(modelACE.Homog, intervals=TRUE)
sumACE.Homog <- summary(fitACE.Homog)
And I got the following message:
Error: The reference 'StdVarComp' does not exist. It is used by named reference 'confidence interval StdVarComp'
I am guessing that I have a simple syntax mistake, but cannot find it.
Do you have any idea what I did wrong?
Thank you very much
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In reply to ran into the same problem by lior abramson
I don't see anything wrong
mxEval(StdVarComp, modelACE.Homog, TRUE)
and from
fitACE.Homog <- mxRun(modelACE.Homog, intervals=TRUE)
(i.e. using
mxRun()
instead ofmxTryHardOrdinal()
and without first usingmxAutoStart()
).Log in or register to post comments
In reply to Thanks for your help. I was by Sabha
To add to mikes reply: You
i.e., you can't just ask for mxCI("ACE.A/ACE.Vtot"), you have to create
mxAlgebra(ACE.A/ACE.Vtot, name="stdA")
mxCI(c('stdA')
On that note, wouldn't it be great if you could just include things in the mxCI statement and they would be automagically created!!
All the information is there.
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In reply to To add to mikes reply: You by tbates
You spelled my wish.
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Hi, I followed
I'm pretty new to OpenMx and R. Could anyone help me generate the 95%CI for standardized A, C, E? Thanks!
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In reply to Hi, I followed by danioreo
Add algebras to your mxModel and request CIs for them
If you want them for the path coefficients, see my post in this other thread: http://openmx.psyc.virginia.edu/thread/2835 .
If you want them for the variance components, try adding something like the following to either your MZ-twin or DZ-twin submodel (it should not matter which):
mxMatrix(type="Full",nrow=3,ncol=1,free=T,values=.6,labels=c("a","c","e"),name="ace"),
mxAlgebra( (ace%^%2) %x% solve(t(ace)%*%ace), name="StdVarComp",dimnames=list(c("a2","c2","e2"),NULL) ),
mxCI("StdVarComp"),
I am assuming here that the single-headed paths going from the latent A, C, and E to the manifest variables are respectively labeled
"a"
,"c"
, and"e"
, as in UnivariateTwinAnalysis_PathRaw.R . Also, depending on where in themxModel()
statement you put this code, you might need to delete that last comma. Then, when you usemxRun()
, be sure to include argumentintervals=TRUE
. You can see the CIs in the output fromsummary(twinACEFit)
or whatever.What the code is doing is creating an
mxMatrix
to hold the path coefficients, because we're going to calculate something from them with anmxAlgebra
, and algebras require matrices. What the algebra does is square each path coefficient, turning them into raw (unstandardized) variance components, and then divide them by the sum of their squares which is equal to the total phenotypic variance. The result is that raw variance components get divided by total variance, yielding standardized components--estimates of the phenotype's narrow-sense heritability, shared-environmentality, and unshared-environmentality.Log in or register to post comments
In reply to Add algebras to your mxModel and request CIs for them by RobK
Thank you for solving my problem
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In reply to Thank you for solving my problem by danioreo
You're welcome. Glad to be
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In reply to You're welcome. Glad to be by RobK
95% CI using bootstrap
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In reply to 95% CI using bootstrap by martonandko
mxBootstrap()
?mxBootstrap
the function call looks like this:
mxBootstrap(model, replications=200, ...,
data=NULL, plan=NULL, verbose=0L,
parallel=TRUE, only=as.integer(NA),
OK=mxOption(model, "Status OK"), checkHess=FALSE)
I can't remember in which version this first appeared.
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CI estimation of univariate genetic model
I have added these codes to the above scripts ,
ci <- mxCI(c("StPathA","StPathC","StPathE","PropVA", "PropVC", "PropVE",
"corA","corC","corE", "corP"))
CholAceModel <- mxModel( "CholACE", pars, modelMZ, modelDZ, minus2ll, obj, ci )
# Run Cholesky Decomposition ACE model
CholAceFit <- mxRun(CholAceModel, intervals=T)
But i still can't obtain that result I wanted.
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In reply to CI estimation of univariate genetic model by Nengzhi
Concerning the change in
LL_ACE <- twinACEFit$output$fit
I can tell from your script that you already know how to calculate LRT statistics, but to get a p-value from each, use
pchisq()
, with the appropriate df and with argumentlower.tail=FALSE
.Concerning confidence intervals: the first argument to
mxCI()
has to be a vector of character strings, with each string referring to a named entity--a labeled path or parameter, an MxMatrix, or an MxAlgebra--in the MxModel object's namespace. The call tomxCI()
in your post does not reference any named entities in the namespace of MxModeltwinACEModel
. As has been stated previously in this thread, you'll need to create MxAlgebras that calculate the quantities of interest, put them into your MxModel, and request CIs for them. For instance, to get a CI for the raw and standardized additive-genetic variance components, create the followoing objects,va <- mxAlgebra(a^2, "Va")
v <- mxAlgebra( (a^2)+(c^2)+(e^2), "Vp")
stva <- mxAlgebra( Va/Vp, "StVa")
ci <- mxCI(c("Va","StVa"))
, and put them into your MZ or DZ submodel (it should not matter which).
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In reply to Concerning the change in by AdminRobK
Yep, and mxCompare()
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In reply to Concerning the change in by AdminRobK
P value
# AE model
# path coefficients for twin 1
pathAceT1 <- mxPath( from=c("A1","C1","E1"), to=selVars[1], arrows=1,
free=c(T,F,T), values=c(.6,0,.6), label=c("a","c","e") )
# path coefficients for twin 2
pathAceT2 <- mxPath( from=c("A2","C2","E2"), to=selVars[2], arrows=1,
free=c(T,F,T), values=c(.6,0,.6), label=c("a","c","e") )
# Combine Groups
paths <- list( latVariances, latMeans, obsMeans,
pathAceT1, pathAceT2, covC1C2 )
aceMat <- mxMatrix(type="Full",nrow=3,ncol=1,free=T,values=.5,labels=c("a","c","e"),name="ace")
StdVarCompAlg <- mxAlgebra( (ace%^%2) %x% solve(t(ace)%*%ace), name="StdVarComp", dimnames=list(c("a2","c2","e2"),NULL) )
mxCI("StdVarComp")
modelMZ <- mxModel(model="MZ", type="RAM", manifestVars=selVars,
latentVars=aceVars, paths, covA1A2_MZ, dataMZ )
modelDZ <- mxModel(model="DZ", type="RAM", manifestVars=selVars,
latentVars=aceVars, paths, covA1A2_DZ, dataDZ )
minus2ll <- mxAlgebra( expression=MZ.fitfunction + DZ.fitfunction,
name="minus2loglikelihood" )
obj <- mxFitFunctionAlgebra( "minus2loglikelihood" )
modelAE <- omxSetParameters(model=ACEFit,labels="c",free=FALSE,values=0,name="AE")
# Run Model
AEFit <- mxRun(modelAE,intervals=TRUE)
AESum <- summary(AEFit)
# Fit AE model
# -----------------------------------------------------------------------------
# Generate & Print Output
M <- mxEval(mean, AEFit)
A <- mxEval(a*a, AEFit)
C <- mxEval(c*c, AEFit)
E <- mxEval(e*e, AEFit)
V <- (A+C+E)
a2 <- A/V
c2 <- C/V
e2 <- E/V
estAE <- rbind(cbind(A, C, E),cbind(a2, c2, e2))
LL_AE <- mxEval(fitfunction, AEFit)
LRT_ACE_AE <- LL_AE - LL_ACE
estACE
estAE
LRT_ACE_AE
# Get Model Output
# -----------------------------------------------------------------------------
# AE model details
AESum
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In reply to P value by Nengzhi
ProTip: It's a good idea to
?pchisq
.Concerning your script in particular, try this:
pchisq(q=LRT_ACE_AE,df=1,lower.tail=FALSE)
The
df=1
is because there is a difference of 1 in the number of free parameters in the ACE model versus the AE model. This command will give you the p-value for the test of the null hypothesis that C variance is zero (when both A variance and E variance are free).Log in or register to post comments
In reply to ProTip: It's a good idea to by AdminRobK
mxCompare too
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CI estimation of univariate genetic model
# Combine Groups
paths <- list( latVariances, latMeans, obsMeans,
pathAceT1, pathAceT2, covC1C2 )
aceMat <- mxMatrix(type="Full",nrow=3,ncol=1,free=T,values=.5,labels=c("a","c","e"),name="ace")
StdVarCompAlg <- mxAlgebra( (ace%^%2) %x% solve(t(ace)%*%ace), name="StdVarComp", dimnames=list(c("a2","c2","e2"),NULL) )
mxCI("StdVarComp")
modelMZ <- mxModel(model="MZ", type="RAM", manifestVars=selVars,
latentVars=aceVars, paths, covA1A2_MZ, dataMZ )
modelDZ <- mxModel(model="DZ", type="RAM", manifestVars=selVars,
latentVars=aceVars, paths, covA1A2_DZ, dataDZ )
minus2ll <- mxAlgebra( expression=MZ.fitfunction + DZ.fitfunction,
name="minus2loglikelihood" )
obj <- mxFitFunctionAlgebra( "minus2loglikelihood" )
modelACE <- mxModel(model="ACE", modelMZ, modelDZ, minus2ll, obj, aceMat, StdVarCompAlg, mxCI("StdVarComp"))
# Run Model
ACEFit <- mxRun(modelACE,intervals=TRUE)
ACESum <- summary(ACEFit)
ACESum
Then, I obtained the CI for ACE. However, when I used the same scripts to run AE model as this:
# Combine Groups
paths <- list( latVariances, latMeans, obsMeans,
pathAceT1, pathAceT2, covC1C2 )
aceMat <- mxMatrix(type="Full",nrow=3,ncol=1,free=T,values=.5,labels=c("a","c","e"),name="ace")
StdVarCompAlg <- mxAlgebra( (ace%^%2) %x% solve(t(ace)%*%ace), name="StdVarComp", dimnames=list(c("a2","c2","e2"),NULL) )
mxCI("StdVarComp")
modelMZ <- mxModel(model="MZ", type="RAM", manifestVars=selVars,
latentVars=aceVars, paths, covA1A2_MZ, dataMZ )
modelDZ <- mxModel(model="DZ", type="RAM", manifestVars=selVars,
latentVars=aceVars, paths, covA1A2_DZ, dataDZ )
modelAE <- mxModel(model="AE", modelMZ, modelDZ, minus2ll, obj, aceMat, StdVarCompAlg, mxCI("StdVarComp"))
an error happened:
> # Run Model
> AEFit <- mxRun(modelAE,intervals=TRUE)
Error: In model 'AE' the name 'c' is used as a free parameter in 'AE.ace' and as a fixed parameter in 'MZ.A' and 'DZ.A'
I don't know how to solve the question, could anyone can help me?
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In reply to CI estimation of univariate genetic model by Nengzhi
omxSetParameters()
modelAE <- omxSetParameters(model=ACEfit,labels="c",free=FALSE,values=0,name="AE")
and proceed.
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In reply to omxSetParameters() by AdminRobK
modelE
modelE <- omxSetParameters(model=ACEFit,labels="a",labels="c",free=FALSE,values=0,name="E")
There was an error:
Error in omxSetParameters(model = ACEFit, labels = "a", labels = "c", :
formal argument "labels" matched by multiple actual arguments
Could u please help me rewrite the scripts to get the result of E model?
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In reply to modelE by Nengzhi
c() is your friend
modelE <- omxSetParameters(model=ACEFit,labels="a",labels="c",free=FALSE,values=0,name="E")
isn't valid R syntax. You can't pass two different values for one function argument specified by name like that. What you want to do instead is
modelE <- omxSetParameters(model=ACEFit,labels=c("a","c"),free=FALSE,values=0,name="E")
. The function
c()
is for concatenating multiple values into a vector.It would also work to fix the two free parameters via two calls to
omxSetParameters()
:modelE <- omxSetParameters(model=ACEFit,labels="a",free=FALSE,values=0,name="E")
modelE <- omxSetParameters(model=modelE,labels="c",free=FALSE,values=0)
That's a bit inelegant, though.
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Thank you for your help
Best wishes to you!
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