OpenSEM Forums

Hi guys,

I need help... My PhD thesis is about consumer behaviour analysis. In detail I look at what actions by companies trigger what customer reactions. In my quantitative study, I would like to look at the following dependent variables:

Behavior (with respective items)
Attitude (...)
Emotion (...)

And the following independent variables:

Opportunity for explanation (given/not given)
Alternative presented (yes/no)

My question is... Do I really need SEM? My professor wants me to do so, but I would rather like to use an experimental MANOVA design.

Hi,

I would like to ask if I have considerably positively skewed raw data for my task performance measures, should I: 1) adjust the variables for covariates (e.g. age, sex and years of training) first, and then transform the residuals using maybe box-cox transformation; or 2) transform the raw variables before adjusting for the covariates?

I've initially done (2) but then I noticed in this paper (http://www.ncbi.nlm.nih.gov/pubmed/21336711) that transformation was done on the residuals, which seems to make more sense.

Hi,

I would like to ask is it actually necessary to adjust for sex effects in sex-limitation models? or just adjusting for age would do?

Thanks!

-Yi Ting

Hi OpenMX community!

I have a probably strait forward question. I'm running simple Univariate ACE models with covariates. My dependent variable has non-normal distribution. Should I normalize my data, for example using the R function scale? Should I normalize my covariates also? My estimates only change slightly, my Chi-square values are basically the same, but my CFI and TLI values change a little bit, should this be of concern?

Thanks for your help!

Hello,
First a thank you to this great forum! I am a beginner at twin model and have found it very helpful. I recently ran the Univariate Sex Limitation Model script http://www.vipbg.vcu.edu/HGEN619_2014/twinHet5AceCon.R At the end one runs a Homogeneity ACE model. My understanding is this should produce the same results as running the OpenMx ACE tutorial limited to just the young twins from the psych package, and excluding the opposite sex pairs. http://openmx.psyc.virginia.edu/docs/openmx/latest/GeneticEpi_Matrix.html

Hello everyone! I just had a quick question, if anyone has the time to help.

I'm running a multivariate ACE Cholesky on three variables, and outputting individual pathways a11, a21, a31, etc for a, c, and e, as well as overall heritability and environmental estimates, h2, c2, e2. However, one of those variables, the third input one, had a skewness and kurtosis level just outside acceptable ranges.

Hi,

Hi, I was running the sex limitation model script from http://www.vipbg.vcu.edu/HGEN619_2014/twinHet5AceCon.R and I'm quite surprised that although the initial model fitting shows that the standardized af, cf, ef and am, cm, em values differ greatly, mxCompare reveals no significant difference between the initial model and the homogeneity ACE model. Is there any possible explanation for this?

Thanks!

Here's what I got:
> QualAceSum <- summary(QualAceFit)
> QualAceSum$pa
name matrix row col Estimate Std.Error lbound ubound lboundMet uboundMet

Is it possible to take a latent variable (for example Marketing) as for a composite variable which can be measured through its components ( for example promotional expenditure, price discounts etc). We can always argue that Marketing is itself a measured variable but if we take it as a composite function of all the activities that comprises of marketing then is it possible to use it as a latent variable? Will it violate any principles of SEM or factor analysis ?
A quick response will be highly helpful as I'm reaching the deadline of my project submission and I'm stuck due to this problem.

Hi, I'm new to SEM and I'm trying to build a model of marketing mix using sem.
My question is that is it possible to incorporate an observed variable in the structural component of SEM which has an effect on a latent variable or is being affected by a latent variable?
I have attached a pictoral representation of my question.
Please help.
Thank you in advance,
Sahil.