Not sure what you mean here? It depends what you are classifying as a 'study?' All primary research studies will need to adopt a paradigm i.e. quantitative, qualitative or mixed methods. Secondary studies i.e. meta-analysis, retrospective, concept and discourse analysis etc still have to adopt a paradigm framework. Literature reviews/conceptual/theoretical articles don't have to - but they are often presented (correctly or not) as if they have adopted quantitative or qualitative principles i.e thematic analysis.
Not sure what you mean here? It depends what you are classifying as a 'study?' All primary research studies will need to adopt a paradigm i.e. quantitative, qualitative or mixed methods. Secondary studies i.e. meta-analysis, retrospective, concept and discourse analysis etc still have to adopt a paradigm framework. Literature reviews/conceptual/theoretical articles don't have to - but they are often presented (correctly or not) as if they have adopted quantitative or qualitative principles i.e thematic analysis.
The goal of the former (qualitative) is to discover what variables exist. The goal of the latter (quantitative) is to measure and compare the variables already discovered.
It is not necessary to integrate both (Qualitative & Quantitative) methods into a research study. As Prof. Dean Whitehead has already said, It depends on the nature of your study.