I like critical ethnography as a research method for this type of study because it accommodates quantitative (if interested) as well as  qualitative methods of data collection. Why? Nursing can be conceived as a sub-culture with its own professional cultural values, routines, roles and role boundaries, patterns of work and so on. Nursing operates in an essentially medically, now administratively dominant, corporate cultural environment. Workplace structures and processes influence outcomes, and though often overlooked, this includes nursing outcomes. Measuring the impact of administrative control on the performance of nursing therefore lends itself to being measured by looking at how it impacts the nursing structure, e.g. staffing, number, level, processes, e.g. use of permanent, part-time, casual staffing, reliance on junior or senior staff, reliance on overtime, access to senior staff, support, promotional opportunities ... and outcomes, e.g. job satisfaction, morale, absenteeism, turnover, accidents and injuries, sick leave, stress, burnout... Literature on job satisfaction, magnet hospitals and transformational leadership could provide more tips for measuring positive impacts on nursing.

Merylin Cross  thank you very much

The Magnet Hospital criteria, created by ANA may be also helpful to you

https://en.wikipedia.org/wiki/Magnet_Recognition_Program

Janet Thurston thank you