The 4 levels of Mixed Methods Research in the agile literature review approach

The 4 levels of Mixed Methods Research in the agile literature review approach (ALRA): [from level 0 to level 3]

Level 0: at the "theoretical framework level 1c" overall level: using both qualitative and quantitative research methods at the overall research methodology level, encompassing all the high-level research tasks of the theoretical framework.

Level 1: at the "theoretical framework level 1c" zone level: using both qualitative and quantitative research methods at the individual zone of the theoretical framework, encompassing all the high-level research tasks of an individual theoretical framework zone.

Level 2: at the "theoretical framework level 1c" item level: using both qualitative and quantitative research methods on an individual item of the theoretical framework. [An individual item in the theoretical framework is a high-level research task (also a research objective)].

Lever 3: at the "theoretical framework level 1c" research method level: e.g. a questionnaire survey research could include questions that make use of rating scale (quantitative) as well as questions that are open-ended (qualitative).

Regarding the diagram, usage of mixed methods research at level 2 [item level] takes place at items 4 and 9, assuming that one of the overlapping research method is quantitative and the other one is qualitative.

For information about the mixed methods research, take a look at the blog note on the onion model. Also study the video on mixed methods philosophy.