Over the past two decades, coaching has shown a rise in popularity that seems unstoppable. In this first chapter, it will be discussed what it means to be a master in coaching and how to measure coaching. Further, a brief discussion of the existing literature about the effectiveness of coaching will be discussed. Yet, what is coaching? And what is meant by 'mastery' in coaching? Using the term 'mastery' already indicates that coaching is a skill. Although scientific knowledge underlies this skill, coaching is foremost about the application of the skill, similar to that a chef of surgeon has to understand the science of food or the human body, as well as being able to master the use of their tools.

How to assess coaching?

While competencies have emerged over the past years, work needs to be done to refine these, making them more behaviourally based, so it is possible to observe the behaviour during an assessed coaching session, as well as to underpin each aspect with evidence. This is a hard task and the field is still struggling to fully achieve this after more than fifty years of attempts of codifying intervention methods. Despite some challenges, we now have methods for assessing levels of competence and thus mastery and an evidence base which supports our knowledge of whether coaching works, what coaching can positively impact upon and how it works. 

What are the characteristics of the AC Executive Coaching Framework?

To assess coaching, a number of models of competence have been offered. One of these, is called the AC's Executive Coaching Framework, which can be visualized by three overlapping constructs: (1) relationship; (2) being, and; (3) doing. AC stands for Association for Coaching, a professional organization that played a significant role in the development and professionalization of coaching. The Association for Coaching Framework uses the following coach competencies for general or all coaches:

1. Meeting ethical, legal and professional guidelines.
   Example indicators of competence: (a) acts ethically and with the highest integrity; (b) clearly communicates how coaching is different from other helping professions. 
2. Establishing the coaching agreement and outcomes.
   Example indicators of competence: (a) clearly explains the coaching process and own coaching approach, models and techniques; (b) helps the client to establish coaching goals and outcomes and agrees an approach to working with the client that will achieve them.
3. Establishing a trust-based relationship with the client.
   Example indicators of competence: (a) treats people equally and fairly, with respect and dignity; (b) is optimistic for and encourages self-belief in the client.
4. Managing self and maintaining coaching presence.
   Example indicators of competence: (a) pays close attention to the client, staying fully present and engaged; (b) remains focuses on the agreed client agenda and outcomes.
5. Communicating effectively.
   Example indicators of competence: (a) communicates clearly, confidently and credibly with the client; (b) adapts communication style to reflect the client's needs and outcomes.
6. Raising awareness and insight.
   Example indicators of competence: (a) asks questions to challenge the assumptions of the client, to elicit new insights and to raise self-awareness and gain learning; (b) helps to broaden a client's perception of an issue and challenges to stimulate new possibilities.
7. Designing strategies and actions.
   Example indicators of competence: (a) supports the client to build strategies to meet their outcome; (b) provides support while the client tries out new ways of working/behaviours.
8. Maintaining forward momentum and evaluation.
   Example indicators of competence: (a) maintains an outcome-focuses approach; (b) checks and acknowledges client progress and achievements.
9. Undertaking continuous coach development.
   Example indicators of competence: (a) regularly requests client feedback; (b) participates in regular coaching supervision to reflect on, and improve, own practice.

Additionally, some additional competencies are formulated for executive coaches:

1. Working within the organizational context.
   Example indicators of competence: (a) understands the organizational context in which the client operates, that is, is aware of the long term vision, mission, values, strategic objectives, competitive pressures and so on; (b) is aware of, and works with, the organization's values, policies and practices, including human resource and people policies and practices. 
2. Understanding leadership issues.
   Example indicators of competence: (a) recognizes the challenges faced by leaders working in organizations; (b) identifies ways of, and opportunities for, developing leadership behaviours and attributes through coaching.
3. Working in partnership with the organization.
   Example indicators of competence: (a) develops relevant networks and strategic partnerships in the organization; (b) identifies ways of adding value to the client at both the individual, team, and organizational level. 

Is coaching magic?

Still too often, people lay claim to the 'magic of coaching', or that coaching is the solution to all organizational and personal problems, like a 'silver bullet'. However, coaching is no magic, and the coach is not a magician. Scientific research has come to the general conclusion that outcomes are influenced by the ability of the coach to build and maintain a relationship with their client, along with wider competence in adapting to and working with a wide range of individuals, issues and frameworks responding in the moment flexibility and empathically towards their client. In fact, the number of such randomized controlled trial (RCT) studies has rapidly increased since 2000, showing the positive effects of coaching on client's wellbeing, learning and skills development. Research has also shown that change is hard work and occurs slowly over time. The work achieved by clients, supported by their coaches, is not magic, but human.

Recently, statistical techniques have allowed meta-studies to supersede the RCT studies as the ultimate research methodology for demonstrating impact, as measured by effect size, often described as g. The effect size is considered small if it is below 0.3. It is moderate between 0.31 and 0.5, and it is considered large when it is over 0.5. Meta-analysis involves combining research from different RCT studies, with the aim of identifying patterns among study results. In the simplest form, the average effect size from the included studies is used. Next, it is weighted relative to the sample sizes within the individual studies, to reduce the impact of small-scale studies on the overall results. By combining results, meta-analysis removes variables such as differences in individual population groups, researchers or individual coaches. The meta-analysis results provide therefore a more accurate view as to the effect or impact of a particular method. 

Recent meta-studies combined with the growing literature on coaching using RCT methodologies, provides conclusive evidence that coaching does work. With this knowledge, practitioners can now support their claims with scientific evidence. The power of coaching is not magic, it is science.