Essam:

Using a mixed methods design could be useful here. You would need to choose a suitable design for mixing your subjective and objective data. Here's what's available on RG that could help you choose a suitable design:

https://www.researchgate.net/search.Search.html?type=publication&query=mixed%20methods%20research&tabViewId=57d98d00ed99e1c0e9362915&previous=researcher

Best regards,

Debra

I appreciate your contribution, Dear Debra. It is a useful resource, thanks!

Hi Dr. Al-Moraissi,

I do not know if there is one correct answer for this situation. What I would do, is to standardize the measures and try to combine them, but also to stratify by the type of measure or analyze separately as well.  I would want to make sure that I am not getting a different picture by combining than I would if I kept the studies with different measures separate.

Warm regards,

Kim

Hi Dr. Keturah,

Thanks for your answer

Do you mean using SMD?

Please be advise data is binary 

Oh, I misunderstood and thought it was data from a scale (continuous).  You do not need to standardize if it is binary.

You mean, Is it valid statistically  and logically to combine it?

There is not a problem statistically.  You can test the logic by looking at the same data combined and separately.  I think if you are open about your approach, others will see your logic.