Sibsankar - if you want to combine both quantitative and qualitative approaches - then the best approach is mixed methods. You can use common quantitative tools, in the quantitative phase, that are non-probability. A classic would be survey design.

Sibsankar - if you want to combine both quantitative and qualitative approaches - then the best approach is mixed methods. You can use common quantitative tools, in the quantitative phase, that are non-probability. A classic would be survey design.

Sibsankar - if you want to combine both quantitative and qualitative approaches - then the best approach is mixed methods research as highlighted by Dean Whitehead or you can carry out a quantitative study as a follow up on findings from qualitative data. Thus, by using both types of research, the strengths of each approach can make up for the weaknesses of the other.

Sibsankar, See the following in my publications list as an example of using a mixed methods approach: Assessment of the factors influencing the duration of Exclusive Breastfeeding in Azerbaijan

Since you are interested in migration, you might take a look at the Journal of Mixed Methods Research special issue on migration, October, 2018.

A qualitative research could be done initially from the experts to see which variable impact the said dependent variable.Once the same are listed,these could be validated through a quantitative research.

I recommend you start to identify the benefit of each expected result and see how it might line up in your report. You can mix both data types to answer one research question or you can have research questions for each. You need to look how you get a "story line", which is challenging in mixed methods. Try to identify a table with your research questions, expected answers and how you are going to treat your answers in your report. I know this is a short answer from me, but you need to start somewhere.

It depends of the research study. Sometimes it may required to use both to gain the proper result.