Hi everyone
I am a newcomer to SEM and I have encountered a problem with AMOS. Given that my data is not multivariate normally distributed and the sample for some of my analyses is small (n=190) I want to use bootstrapping in AMOS. So, I've taken one of the models I tested by means of maximum likelihood estimation as a baseline, have selected a new SPSS file containing raw data where I had eliminated all the cases with missing values on any of the variables in the model as the data file and then ran the analysis with this sample.
First I tested for multivariate non-normality by looking at the assessment of normality. As expected the data turned out not to be normally distributed. Next, I used the Bollen-Stine Bootstrap to test the overall fit of the model. This worked fine.
Then I wanted to have a look at the bootstrap parameter estimates. In the Anylysis Properties -> Bootstrap tab I deselected the Bollen-Stine bootstrap and selected perform bootstrat, percentile confidence intervals and Bias-corrected intervals.
When I view the text output after running this,
only the non-bootstrapped estimate output is available. Or at least I
think so, because the output tables do not contain the columns SE ...
SE/SE ... Mean ... Bias ... SE Bias.
The directory for the bootstrap output is shown in the second row of
the left-hand column on the output window. This says Estimates /
Bootstrap > Estimates > Bootstrap standard error > Bootstrap
Confidence. The second line ("Estimates") is in grey, suggesting it is
inactive. I can't click on any of these links, and hence can't see any
of the bootstrapped estimates.
I assume that the bootstrapping worked, because the following
information is displayed under the Summary of Bootstrap link:
0 bootstrap samples were unused because of a singular covariance matrix.
2 bootstrap samples were unused because a solution was not found.
200 usable bootstrap samples were obtained.
Does anyone have an idea why I can't view the bootstrap estimates?
Is there something I might have forgotten, like fixing certain parameters? But I don't get any AMOS warnings that something is amiss. Furthermore, the Bollen-Stine bootstrap worked just fine. So why doesn't this work?
Thank you so much for your help!
Sybille
I am a newcomer to SEM and I have encountered a problem with AMOS. Given that my data is not multivariate normally distributed and the sample for some of my analyses is small (n=190) I want to use bootstrapping in AMOS. So, I've taken one of the models I tested by means of maximum likelihood estimation as a baseline, have selected a new SPSS file containing raw data where I had eliminated all the cases with missing values on any of the variables in the model as the data file and then ran the analysis with this sample.
First I tested for multivariate non-normality by looking at the assessment of normality. As expected the data turned out not to be normally distributed. Next, I used the Bollen-Stine Bootstrap to test the overall fit of the model. This worked fine.
Then I wanted to have a look at the bootstrap parameter estimates. In the Anylysis Properties -> Bootstrap tab I deselected the Bollen-Stine bootstrap and selected perform bootstrat, percentile confidence intervals and Bias-corrected intervals.
When I view the text output after running this,
only the non-bootstrapped estimate output is available. Or at least I
think so, because the output tables do not contain the columns SE ...
SE/SE ... Mean ... Bias ... SE Bias.
The directory for the bootstrap output is shown in the second row of
the left-hand column on the output window. This says Estimates /
Bootstrap > Estimates > Bootstrap standard error > Bootstrap
Confidence. The second line ("Estimates") is in grey, suggesting it is
inactive. I can't click on any of these links, and hence can't see any
of the bootstrapped estimates.
I assume that the bootstrapping worked, because the following
information is displayed under the Summary of Bootstrap link:
0 bootstrap samples were unused because of a singular covariance matrix.
2 bootstrap samples were unused because a solution was not found.
200 usable bootstrap samples were obtained.
Does anyone have an idea why I can't view the bootstrap estimates?
Is there something I might have forgotten, like fixing certain parameters? But I don't get any AMOS warnings that something is amiss. Furthermore, the Bollen-Stine bootstrap worked just fine. So why doesn't this work?
Thank you so much for your help!
Sybille