Displaying 20 results from an estimated 6000 matches similar to: "Imputing data below detection limit"
2011 Dec 02
2
Imputing data
So I have a very big matrix of about 900 by 400 and there are a couple of NA
in the list. I have used the following functions to impute the missing data
data(pc)
pc.na<-pc
pc.roughfix <- na.roughfix(pc.na)
pc.narf <- randomForest(pc.na, na.action=na.roughfix)
yet it does not replace the NA in the list. Presently I want to replace the
NA with maybe the mean of the rows or columns or
2010 Jul 14
1
Changing model parameters in the mi package
I am trying to use the mi package to impute data, but am running into
problems with the functions it calls.
For instance, I am trying to impute a categorical variable called
"min.func." The mi() function calls the mi.categorical() function to
deal with this variable, which in turn calls the nnet.default()
function, and passes it a fixed parameter MaxNWts=1500. However, as
2008 Dec 22
1
imputing the numerical columns of a dataframe, returning the rest unchanged
Hi R-experts,
how can I apply a function to each numeric column of a data frame and return
the whole data frame with changes in numeric columns only?
In my case I want to do a median imputation of the numeric columns and
retain the other columns. My dataframe (DF) contains factors, characters and
numerics.
I tried the following but that does not work:
foo <- function(x){
2012 Dec 08
1
imputation in mice
Hello! If I understand this listserve correctly, I can email this address
to get help when I am struggling with code. If this is inaccurate, please
let me know, and I will unsubscribe.
I have been struggling with the same error message for a while, and I can't
seem to get past it.
Here is the issue:
I am using a data set that uses -1:-9 to indicate various kinds of missing
data. I changed
2004 Sep 01
3
Imputing missing values
Dear all,
Apologies for this beginner's question. I have a
variable Price, which is associated with factors
Season and Crop, each of which have several levels.
The Price variable contains missing values (NA), which
I want to substitute by the mean of the remaining
(non-NA) Price values of the same Season-Crop
combination of levels.
Price Crop Season
10 Rice Summer
12
2007 Jun 22
1
Imputing missing values in time series
Folks,
This must be a rather common problem with real life time series data
but I don't see anything in the archive about how to deal with it. I
have a time series of natural gas prices by flow date. Since gas is not
traded on weekends and holidays, I have a lot of missing values,
FDate Price
11/1/2006 6.28
11/2/2006 6.58
11/3/2006 6.586
11/4/2006 6.716
11/5/2006 NA
11/6/2006 NA
11/7/2006
2008 Mar 05
1
rrp.impute: for what sizes does it work?
Hi,
I have a survey dataset of about 20000 observations
where for 2 factor variables I have about 200 missing
values each. I want to impute these using 10 possibly
explanatory variables which are a mixture of integers
and factors.
Since I was quite intrigued by the concept of rrp I
wanted to use it but it takes ages and terminates with
an error. First time it stopped complaining about too
little
2011 Feb 07
1
multiple imputation manually
Hi,
I want to impute the missing values in my data set multiple times, and then
combine the results (like multiple imputation, but manually) to get a mean
of the parameter(s) from the multiple imputations. Does anyone know how to
do this?
I have the following script:
y1 <- rnorm(20,0,3)
y2 <- rnorm(20,3,3)
y3 <- rnorm(20,3,3)
y4 <- rnorm(20,6,3)
y <- c(y1,y2,y3,y4)
x1 <-
2010 Aug 10
1
Multiple imputation, especially in rms/Hmisc packages
Hello, I have a general question about combining imputations as well as a
question specific to the rms and Hmisc packages.
The situation is multiple regression on a data set where multiple
imputation has been used to give M imputed data sets. I know how to get
the combined estimate of the covariance matrix of the estimated
coefficients (average the M covariance matrices from the individual
2010 Nov 01
1
Error message in fit.mult.impute (Hmisc package)
Hello,
I would like to use the aregImpute and fit.mult.impute to impute missing
values for my dataset and then conduct logistic regression analyses on the
data, taking into account that we imputed values. I have no problems
imputing the values using aregImpute, but I am getting an error at the
fit.mult.impute stage.
Here is some sample code (I actually have more observations and variables to
2005 Jan 11
1
transcan() from Hmisc package for imputing data
Hello:
I have been trying to impute missing values of a data
frame which has both numerical and categorical values
using the function transcan() with little luck.
Would you be able to give me a simple example where a
data frame is fed to transcan and it spits out a new
data frame with the NA values filled up?
Or is there any other function that i could use?
Thank you
avneet
=====
I believe in
2004 Mar 15
2
imputation of sub-threshold values
Is there a good way in R to impute values which exist,
but are less than the detection level for an assay?
Thanks,
Jonathan Williams
OPTIMA
Radcliffe Infirmary
Woodstock Road
OXFORD OX2 6HE
Tel +1865 (2)24356
2011 Mar 31
2
fit.mult.impute() in Hmisc
I tried multiple imputation with aregImpute() and
fit.mult.impute() in Hmisc 3.8-3 (June 2010) and R-2.12.1.
The warning message below suggests that summary(f) of
fit.mult.impute() would only use the last imputed data set.
Thus, the whole imputation process is ignored.
"Not using a Design fitting function; summary(fit)
will use standard errors, t, P from last imputation only.
Use
2011 Jun 23
2
Rms package - problems with fit.mult.impute
Hi!
Does anyone know how to do the test for goodness of fit of a logistic model (in rms package) after running fit.mult.impute?
I am using the rms and Hmisc packages to do a multiple imputation followed by a logistic regression model using lrm.
Everything works fine until I try to run the test for goodness of fit: residuals(type=c("gof"))
One needs to specify y=T and x=T in the fit. But
2003 Jul 27
1
multiple imputation with fit.mult.impute in Hmisc
I have always avoided missing data by keeping my distance from
the real world. But I have a student who is doing a study of
real patients. We're trying to test regression models using
multiple imputation. We did the following (roughly):
f <- aregImpute(~ [list of 32 variables, separated by + signs],
n.impute=20, defaultLinear=T, data=t1)
# I read that 20 is better than the default of
2008 Nov 26
1
multiple imputation with fit.mult.impute in Hmisc - how to replace NA with imputed value?
I am doing multiple imputation with Hmisc, and
can't figure out how to replace the NA values with
the imputed values.
Here's a general ourline of the process:
> set.seed(23)
> library("mice")
> library("Hmisc")
> library("Design")
> d <- read.table("DailyDataRaw_01.txt",header=T)
> length(d);length(d[,1])
[1] 43
[1] 2666
2003 Dec 08
1
Design functions after Multiple Imputation
I am a new user of R for Windows, enthusiast about the many functions
of the Design and Hmisc libraries.
I combined the results of a Cox regression model after multiple imputation
(of missing values in some covariates).
Now I got my vector of coefficients (and of standard errors).
My question is: How could I use directly that vector to run programs such
as 'nomogram', 'calibrate',
2011 Oct 10
1
Multiple imputation on subgroups
Dear R-users,
I want to multiple impute missing scores, but only for a few subgroups in my
data (variable 'subgroups': only impute for subgroups 2 and 3).
Does anyone knows how to do this in MICE?
This is my script for the multiple imputation:
imp <- mice(data, m=20, predictorMatrix=pred, post=post,
method=c("", "", "", "",
2007 Sep 26
1
using transcan for imputation, categorical variable
Dear all,
I am using transcan to impute missing values (single imputation). I have
several dichotomous variables in my dataset, but when I try to impute
the missings sometimes values are imputed that were originally not in
the dataset. So, a variable with 2 values (severe weight loss or
no/limited weight loss) for example coded 0 and 1, shows 3 different
values after imputation (0, 1 and 2).
I
2005 May 04
3
Imputation
I have timeseries data for some factors, and some missing values are there in those factors, I want impute those missing values without disturbing the distribution of that factor, and maintaining the correlation with other factors. Pl. suggest me some imputation methods.
I tried some functions in R like aregImpute, transcan. After the imputation I am unable to retrive the data with imputed