Hi, I'm trying to get my head around the jamovi reliability analysis, and in particular using omega as a reliability measure.

My understanding of this is based on reading William Revelle:

http://www.personality-project.org/r/book/Chapter7.pdf

http://personality-project.org/r/psych/HowTo/factor.pdf

Here's my questions:

1. It seems like there are two omega values - omegaH and OmegaT. Which does jamovi report?

2. Is it possible to calculate omega reliabilities using polychoric correlations (ie the equivalent of setting poly=TRUE in the omega function in R). Is this necessary for working out reliabilities on data from Likert scales?

3. What is the equivalent R procedure (without using jmv) to produce a list of 'if item dropped' omega values?

4. The Revelle references explain omega calculations as involving an EFA plus some other steps. It seems like the default option for the psych omega function is to calculate an EFA with 3 factors. Is that also what jamovi does? If so, is that going to be ok for all datasets? Are there any situations where we would need to specifiy a different number of factors?

5. A slight bug: From the Reliability Analysis screen, if I clear all variables out of the 'items' selection box, this does not automatically clear items from the 'Reverse Scaled Items' box and causes an error.

Thanks for any clarity on these points.