Introducing key variables (Move 6, Step 1)

Here is in example from a study in the field of management that examined research productivity of graduate students in Korea. Note the phrases that signal how the authors define the key variables.

Example

The Impact of Graduate Students on Research Productivity in Korea

Methodology
The goal of this study is to analyze differences in researchers’ productivity in relation to the number of graduate students they manage. The independent variable, graduate students, refers to the number of graduate students that each respective researcher hires; this figure was obtained in 2009 by the number of graduate students involved in the projects that NRF supported from 2005 to 2007. The dependent variable, research productivity, was defined as research career. This was calculated by dividing the number of papers produced by each researcher in 2008 into Korea Citation Index (KCI) and Science Citation Index (SCI) scores measuring domestic and foreign publication, respectively. For co-authored papers, individual paper outcomes were divided by the total number of authors (n +2).

Control variables were gender, amount of funding (government-funded, enterprisefunded, or university-funded), age, institution trained (domestic or foreign) where researchers obtained their degree, region (capital or non-capital), and researchers’ disciplines. Age was calculated by adding squared terms, in accordance with previous findings that researchers’ careers have a quadratic function form characterized by negative values associated with higher age (Baser and Pema 2004; Oster and Hamermesh 1998; Kenny and Studley 1996; Kyvik 1990; Diamond 1980).

Source: Kwon, K-S., Kim, S., Park, T-S., Kim, E., & Jang, D. (2015). The impact of graduate students on research productivity in Korea. Journal of Open Innovation: Technology, Market, and Complexity, 1(21).