similar to: Tetrachoric and polychoric ceofficients (for sem) - any tips?

Displaying 20 results from an estimated 2000 matches similar to: "Tetrachoric and polychoric ceofficients (for sem) - any tips?"

2004 Dec 09
1
Re: Tetrachoric and polychoric correlations, Polycor package
A bit late, but you might like to look at http://www.qimr.edu.au/davidD/polyr.R Regarding the original posters queries: You can analyse polychoric correlations as if they were Pearson correlations using standard software (eg sem), and this usually doesn't do too badly, or go to AWLS (Browne) in LISREL etc, or ML analysis of the full multidimensional contingency table using programs such as
2008 Sep 01
1
Polychoric and tetrachoric correlation
Hi there, Am I correct to believe that tetrachoric correlation is a special case of polychoric correlation when there are only two levels to the ordered factor? Thus it should be okay to use hetcor from the polycor package to build a matrix of correlations for binary variables? If this is true, how can one estimate 95% confidence intervals for the correlations? My guess would be mat =
2010 Apr 02
2
tetrachoric correlations
Hi, Is there any R library/package that calculates tetrachoric correlations from given marginals and Pearson correlations among ordinal variables? Inputs to polychor function in polycor package are either contingency tables or ordinal data themselves. I am looking for something that takes marginal distributions and Pearson correlation as inputs. For example, Y1=(1,2,3) with P(Y1=1)=0.3,
2007 Aug 12
1
SEM for categorical data
Hi I am looking for a structural equation modeling package in R which can be used for categorical data. Is anyone aware of the existence of such a package? Would appreciate any help on this. Thank you Upasna -- --------------------------------------------------------------------- Upasna Sharma Research Scholar Shailesh J. Mehta School of Management, Indian Institute of Technology, Bombay
2005 Apr 18
1
polycoric correlation
Dear R-users Could anyone tell me which library contains a function to compute polycoric correlations? I wonder the same question was asked a while ago, but I could not locate the mail in the R-help archives. Sorry for bothering you. Sincerely ------------------------ Hiroto Miyoshi ???? h_m_ at po.harenet.ne.jp
2009 Jan 12
3
polychoric correlation: issue with coefficient sign
Hello, I am running polychoric correlations on a dataset composed of 12 ordinal and binary variables (N =384), using the polycor package. One of the association (between 2 dichotomous variables) is very high using the 2-step estimate (0.933 when polychoric run only between the two variables; but 0.801 when polychoric run on the 12 variables). The same correlation run with ML estimate returns a
2006 Jun 23
2
Tetrachoric correlation in R vs. stata
I hope someone here knows the answer to this since it will save me from delving deep into documentation. Based on 22 pairs of vectors, I have noticed that tetrachoric correlation coefficients in stata are almost uniformly higher than those in R, sometimes dramatically so (TCC=.61 in stata, .51 in R; .51 in stata, .39 in R). Stata's estimate is higher than R's in 20 out of 22
2002 May 01
3
bivariate normal cdf and rho
Suppose F(x, y; rho) is the cdf of a bivariate normal distribution, with standardized marginals and correlation parameter rho. For any fixed x and y, I wonder if F(x, y; rho) is a monotone increasing function of rho, i.e., there is a 1 to 1 map from rho to F(x, y; rho). I explored it using the function pmvnorm in package mvtnorm with different x and y. The plot suggests the statement may be true.
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
2004 Dec 09
0
Re: Polychoric correlations
This is a bit late, but: > About two years ago there was a thread about this which suggested that at > that time nobody had these coefficients ready to go. > (a) has anyone in the meanwhile programmed them? http://www.qimr.edu.au/davidD/R/polyr.R > (d) I appreciate this last item is not strictly an R question, but my > intention is to use these as input into the sem package for
2002 Feb 21
2
Re: Factor analysis of categorical or mixed categorical/continuousdata in
I am looking to fit one or more latent categorical variables to data that is a mixture of categorical and continuous variables. Factor analysis would work for continuous data, latent class analysis for categorical data. I understand that in a package such as MPlus I could perform a single analysis of both data types. Are there similar routines available in R? Stuart -----Original Message-----
2005 Oct 10
1
SEM with dichotomous indicators
Hello, I'd like to know if there is a way to fit a Structural equation model with dichotomous indicators (ex: problem with a phone solved/ or not) having effects on a ordinal variable. How I do that using R? Do you have an example with the code in R that you can send to me? Thanks a lot! Renata Estrella UFRJ, Brasil, Rio de Janeiro Renata Leite Estrella Assistente de
2004 Oct 01
3
Plotting panels at arbitrary places on a map, rather than on a lattice
I think it is easiest to describe what I want in terms of the concrete problem I have. I have data from a number of countries in each of which a sample of people was interviewed. In presenting the results in a forthcoming collaborative publication much emphasis will be placed on the multi-centre nature of the study. Although I suspect colleagues may do this with shaded maps I would prefer to
2008 May 29
1
appropriate covariance matrix for multiple nominal exogenous and multiple continuous endogenous variables in SEM
Hi, I would like to use the sem package to perform a path analysis (no latent variables) with a mixture of 2 nominal exogenous, 1 continuous exogenous, and 4 continuous endogenous variables. I seek advice as to how to calculate the appropriate covariance matrix for use with the sem package. I have read through the polycor package, and am confused as to the use of "numeric" for
2009 Mar 11
2
non-positive definite matrix remedies?
Hi all, For computational reasons, I need to estimate an 18x18 polychoric correlation matrix two variables at a time (rather than trying to estimate them all simultaneously using ML). The resulting polychoric correlation matrix I am getting is non-positive definite, which is problematic because I'm using this matrix later on as if it were a legitimately estimated correlation matrix (in order
2007 Apr 15
1
Fit sem model with intercept
Hi - I am trying to fit sem model with intercepts. Here is what I have in my model. Exogeneous vars: x1 (continous), x2 (ordinal), x3 (ordinal), x4(continuous) Endogeneous vars: y1 (continuous), y2 (ordinal), y3 (ordinal) SEM model: x1 -> eta1; x2 -> eta1; x3 -> eta2; x4 -> eta2; eta1 -> y1, eta1 -> y2, eta2 -> y2, eta2 -> y3 However, in these arrow models, I
2004 Mar 22
2
Lattice, skip= and layout= problem, plotting object from nlme output
I generate a groupedData object library(nlme) obj <- groupedData(mg10 ~ time | gp, data = common, outer = ~pct) gp has 101 levels, and pct has 3. There are 38, 25, 38 gps in each of the levels of pct respectively. I fit my model fit.rtg <- lme(mg10 ~ time * group, data = obj, random = ~time * group | gp) Now I try to plot the results. I would like to print 40 panels on each
2010 Jan 03
1
Questions regarding sem using hetcor() function from polycor and diagrams
Hello R Users, While I have attempted to dig into the R help files and I have not identified the answer to these questions, I apologize in advance if my questions were answered in the past. I also recognize that one of my questions unfortunately verges on statistical rather than code territory. I have two rather unrelated questions about using the sem and polycor packages for a relatively
2007 Dec 19
1
Correlation when one variable has zero variance (polychoric?)
Hi, I'm running this for a simulation study, so many combinations of parameter produce many predictions that I need to correlate with data. The problem ---------------- I'm using rating data with 3 to 5 categories (e.g., too low, correct, too high). The underlying continuous scales should be normal, so I chose the polychoric correlation. I'm using library(polychor) in its
2008 Jan 12
2
Factor Analysis
Good Morning, Is it possible to use the R program for a CFA with dichotomous data? Thank you, Kathleen Kathleen Kemp, M.A. Doctoral Clinical Psychology Student, Concentration: Forensic Psychology Drexel University Philadelphia, PA 19104 kk354@drexel.edu [[alternative HTML version deleted]]