The selection of a research method, be it quantitative, qualitative, or a combination of thereof, must be driven by the substantive content of the research question (or hypothesis). Qualitative research is by definition exploratory: it is used to help define a problem or develop an approach to it when we do not know what to expect. (And so, focus groups, triads, dyads, in-depth interviews, uninterrupted observation, bulletin boards, ethnographic participation/observation, etc.) Conversely, quantitative research is conclusive: it endeavors to quantify a problem and understand how prevalent it is by looking for projectable results. (And so, surveys, audits, points of purchase, click-streams, etc.) It is possible that, a problem having been defined and approaches to it having been developed with qualitative research, a related research question might then invite quantitative research.
If what you want to measure or value are qualitative aspects of management I prefer mixed research with greater relevance of qualitative aspects, but I think you should also incorporate quantitative aspects. In the field of business management, the hows (how things are made) are becoming more important than the what (what have you done).
My preference would depend on the problem and the purpose of the research. The question(s) generated would determine my preferred method. However, during my PhD program, after participating in a survey, I found out that, in my approach to research, I was one of only TWO people in the class who fell comfortably into the mixed methodology category of researchers.
This is widely affected by a set of factors including, but not limited to
1. Research questions (aim and objectives)
2. The context in which data will be collected (national culture, non-profit sector, for-profit sector, public sector, operational management, middle management, top management...,etc).
I used qualitative in my recent study because the topic was not well studied and therefore there was not a hypothesis that reasonably addressed the information I was attempting to analyze. Now that my bigger questions are answers, I will move to mixed methods for follow up research. When I read quant research on leadership, I have too many questions that could only have been answered had qual been included - thus mixed is my preference.
In general, much of the research about leadership is quantitative because there are many well-established instruments available to tease out factors that have been confirmed to be leadership related.
Unfortunately, many of the more subtle and differentiating factors associated with leadership ethics and trust are not measured well -- although instruments nonetheless exist. Much more research needs to be done about measuring factors that affect leadership, its impacts, the response of followers, and the means by which these factors can be applied in organizations.
Much of my research to date has been conceptual in attempting to explore how leadership affects follower responses. Qualitative exploration of leadership behaviors has limited value and is acknowledged to be intended to understand more about leaders -- but is, by its very nature, not representative of much more than the boundary conditions in which that research is conducted.
We need more solid quantitative and mixed research to continue to learn more about leadership that can be generalized . . . .although some excellent work has already been done. We suffer from the reality that leadership is so broadly defined that we often lack commonality of understanding what we are really measuring.