I'm writing a dynamical script which enables the user to select different scales to analyze their reliability. However, I want adress the overall reliability in some kind of global variable. Since the user might select multiple scales which are not related in any empirical or theoretical way, I'm considering just using the mean of the cronbach's alpha value of the selected scales. Is it legitimate to do so?
As internal consistense is a correlation the average across the values is not legit.
- You should use Fisher's z Transformations on your cronbach's alpha values
- Average those z values
- Tranform average z back into cronbach's alpha value
For more details please have a look at http://www.tandfonline.com/doi/abs/10.1080/00221309809595548