To Study Device Attributes by Investigating Errors Made in Use, Ease of Use and Preference Among Different Inhalers in Subjects With Asthma

This is a non-interventional study and not an observational study and therefore some fields are not applicable for the CT.gov observational study design. It would be preferential to have the field populated as "not applicable" for sampling method, time perspective, and observational study model as they don't apply to this study design.