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Leadership & Executive Coaching Effectiveness

Anecdotes are good, data is better. Erik de Haan has published his review of quantitative research on the effectiveness of coaching.

What is this article about?

The effectiveness of leadership & executive coaching: first overview of quantitative studies published by Professor Erik de Haan, current common practices, my approach

-reading time: 4 minutes- / -audience: Leaders, HR, Coaches-

Anecdotes are good, data is better

Coming from the corporate world of industry leaders, I am used to bringing evidence to the table when you want to achieve something. Anecdotes are considered as a welcome complement to higher valued hard data; whether you offer solutions to customers, spend more on marketing efforts or prepare investment appraisals for acquisitions.

In my current role as a Leadership Coach & Developer, I struggle to approach my work similarly; I cannot prove that 10’000 CHF worth of coaching is providing an ROI of 500%.

To partly overcome this hiatus, I use personality and leadership assessments at the beginning of my coaching programs so that my clients and I have an anchor point to start from and can work with actual data. Together with the coachee, we set the main objective to achieve and supporting actions, changes or omissions.

I know from other coaches, that they ask the coachee how a session contributed to dealing with a specific challenge. The coach asks the coachee a pre-session score and a post-session score between 1 and 10; when the post-session score is higher then the session is perceived as good. Without discounting the approach of my colleagues, I prefer to ask this once the coaching has translated into the actual desired impact of the coachee – which may take multiple sessions, or even longer as behavioural and leadership change needs internalisation.

A proxy to obtain insight into the behavioural change or progress of a coachee is to apply 360s and collect feedback, scores or ratings from the coachee’s peers, direct reports and manager.

leadership coaching development STRATZR 360 feedback

During my Master in Coaching & Consulting for Change at HEC Paris & University of Oxford, we dealt with the same issue and fortunately, one of our classmates who has a PhD in Math decided to apply game theory to find out about how to calculate the ROI on coaching.

One example he brought up was that it is sometimes cheaper for a company to increase the salary of an employee than to invest in coaching; the employee could improve her skills which would make her more attractive to competitors. Coaching investment gone, negative ROI. Or an employee would realise that his current job does not fulfill his life’s purpose, so he leaves the company: negative ROI.

Although I dearly wish to provide a solid ROI calculation, I am not worried (yet). No coach can; there is not enough evidence – yet.


But there is good news: Erik de Haan, a Professor at Ashridge and Leadership Developer for whom I have very high esteem, has recently published his new book What Works in Executive Coaching and has reviewed the full coaching outcome research literature (to date) to examine the arguments and evidence behind the use of executive coaching.

I am awaiting the delivery of the book and in the meantime I watched Mick Cooper interviewing Erik de Haan about the effects and impact of coaching as described in his forthcoming book.

Before discussing the findings, Erik de Haan kicks off by stating that in recent years there has been an exponential growth of research in coaching impact and that there finally is enough data to draw some conclusions. However, it is questionable if coaches will make use of it, as there is an apparent disconnect between coaches and quantitative research.

Erik de Haan has collected and researched around 160 published articles with a quantitative base, for example using Randomised Control Trials (RTC, ie. 2 groups of managers of the same company are compared, while one group received coaching and the other group did not).

Erik de Haan perceives that coaching is not about sitting down and listening like a bunch of hippies; the coachee – often also the commissioner – needs statistically proven results and Erik’s research can be used as guidance.

Erik de Haan has over twenty-five years of experience in organisational and personal development, bringing to his work a sensitivity to what moves and motivates people, and a strong analytical ability. He aims to support people in their search for what is ‘right and just’ for themselves and for others in their organisation. Searching for and assuring people’s personal engagement appears to him a key condition for change and development.

Everybody should have a coach

Google CEO Eric Schmidt

My takeaway from the findings


  • Different coaching interventions or coaching approaches do not always lead to different results
  • Even 3 sessions prove to make a difference and executive coaching works; Erik de Haan’s meta-analysis provides evidence that there is a significant effect on the coachee’s surroundings, demonstrating the impact of coaching on others around the coachee
  • 5 to 6 sessions usually have the same effect as 20+ sessions
  • When coaching is about providing support, female coaches seem to have an advantage; however, women working with women and men working with men, makes a bigger difference than cross-gender coaching
  • In case of new tasks or behaviours, a facilitating, inquisitive and listening intervention works best; in the case of improving basic tasks or behaviours, a guiding and consulting approach works best
  • The impact of coaching is visible at all levels in the organisational hierarchy


  • One of the studies provided evidence that new and younger coaches contribute more to the success than long term, older coaches
  • Coaching is most effective when the coach is credible in terms of coachee related experience and knowledge. Also, the background and reputation of the coach have an impact on the perceived effectiveness
  • Credibility, background and reputation leads to trust and openness
  • The coach can achieve the most when the coach is friendly, confident and believes in his/her own approach and method; a positive relationship between the coach and coachee throughout the coaching sessions is essential


  • The effect of coaching, in general, is proven to be experienced in the attainment of the coachee’s own goals, the coachee’s increase in resilience, improved skills and competencies, and higher efficacy
  • Coachees with a strong social support network, already performing well, active in the higher echelon, benefit most from coaching – at the moment, as it may be related to the fact that coaching is still considered to be a luxury service, out of reach for the less fortunate, who can benefit as much from coaching


So according to Erik de Haan, leadership and managerial coaching have a very high level of effectiveness according to research, but more research needs to be done.

From my own experience – and I think many leadership development coaches can relate to this – is that clients perceive coaching as adding value when, for example:

“Successful people have coaches“
  • Anxiety for a new position or responsibilities has reduced to a normal and manageable level
  • Job comfort and satisfaction has increased due to an altered perspective on the content or context
  • Relationships with peers, direct reports and upper level have improved in quality due to enlarged self-awareness, understanding of the shadow and understanding others’ motives, interests, and preferences
  • The team is led more effectively with fewer conflicts, higher engagement and commitment, and greater performance
  • Colleagues in the organisation notice the improvements or changes and express this in a positive way
  • Persuasion power has increased and has led to getting a higher approval rate of committees, leadership or clients
  • …and more

Thank you Erik de Haan, I am looking forward to more research on the effects of executive and leadership coaching!