Table 1 A meta-review of contemporary... | Emerald Publishing

Table 1

A meta-review of contemporary meta-analyses and systematic reviews on coaching

Meta-analysis
References	Coaching types	No. of papers	Main finings	Future suggestions
Theeboom et al. (2014)	Workplace coaching Both external and internal	k = 18	Effect sizes from g = 0.43 (coping) to g = 0.74 (goal-directed self-regulation)	A need for theoretical enrichment, such as self-determent theory (SDT), working alliance, characteristics of coaches and motivational components
Sonesh et al. (2015)	Executive, leadership and business coaching	k = 24	The impact of coaching on overall relationship outcomes was significant (g = 0.32, 95% CI [0.27, 0.38])	To what extent is coaching effectiveness attributable to positive shifts in coachees' relational and psychological states? What specific coach behaviors contribute to a strong positive coach-coachee relationship? What coach behaviors, strategies, and techniques contribute to successful coaching engagements?
Jones et al. (2016)	Workplace coaching Both external and internal	k = 17	Coaching had a positive effect on all outcomes (d = 0.36, 90% CI [0.16, 0.50]) Coaching had greater outcomes when coaching was provided without multisource feedback (d = 0.88 vs d = 0.21) Research design does not appear to moderate the effects of coaching on outcome coaching provided in the face-to-face format with blended formats The effects of coaching on outcomes were weaker for external coaches in comparison with internal coaches Neither longevity in weeks of the coaching intervention nor number of coaching sessions moderated overall coaching effectiveness	To examine cognitive, team or organizational-level results’ outcome criteria To examine how the relative impact of coaching on different kinds of criteria and compare this with other forms of L&D intervention (e.g. training) A need for the development of theory concerning why, how and in what ways coaching leads to the positive effects we reported in this study
Burt and Talati (2017)	Workplace and life coaching	k = 11	Coaching had a moderate significant positive effect on coachees, $\hat{p}$ = 0.42	The need for more performance rating and the coach–coachee relationship evaluation in the coaching literature A need to conduct longitudinal explorations and measure engagement across teams and the wider organizational level outcomes
Graßmann et al. (2020)	Workplace, life and career coaching	k = 27 (n = 3,563)	A moderate and consistent overall relationship between a high-quality working alliance and coaching outcomes for clients (r = 0.41, 95% CI [0.34, 0.48], p < 0.001)	To examine the role of the coaching relationship perspective in more detail
Systematic review
Lai and McDowall (2014)	Workplace, life and personal coaching	k = 140	Key factors for a positive coaching relationship were identified, such as building trust, two-way communication and transparent contracting process Essential attributes required for a professional coach in psychology area: theoretical knowledge (e.g. psychology and leadership), attitude (e.g. non-judgmental) and interpersonal skills	The future research should emphasize on the improvement of research methods and coaching result evaluation approaches to ensure producing more rigorous and replicable study results
Blackman et al. (2016)	Business coaching (external only)	k = 111	Coaching had positive effects on individual L&D outcomes There is no sufficient evidence to indicate coaching was more effective than other L&D approaches Key factors were identified to contribute to effective business coaching outcomes: the coach's (e.g. communication skills) and coachee's (e.g. self-efficacy) characteristics, coach–coachee relationship and organizational context Skills or expertise in the sector or in executive management were preferable	The future research should focus on developing sound theoretical models based on more sophisticated research
Grover and Furnham (2016)	Executive, leadership and business coaching (both external and internal)	k = 52	In general, coaching had positive effects on coachees' self-efficacy Coaching had positive effects on psychological outcomes, such as stress, anxiety, well-being, etc. There were mixed results between coaching and coachees' work or like satisfaction and performance Current research evidence indicated coaching generated longitudinal outcomes; however, more empirical research is required There was no adequate empirical evidence to confirm that coaching had positive impact on organizational-level outcomes Several mechanisms were identified: coachees' self-efficacy and motivation, coaches' interpersonal skills and the quality of coaching relationship, etc.	To establish an independent working group that consists of coaches, academics, organizations that use coaching and any stakeholders, and the research method should include methodological and statistical procedures, minimum sample sizes and a set of outcome variables
Athanasopoulou and Dopson (2018)	Executive coaching (external only)	k = 110	It is difficult to integrate the research evidence due to the diversity of research methods Social context and organizational-level outcomes have been overlooked in current research The research evidence on the effectiveness of coaching was not mixed	The future research should be a more context-sensitive based and better research designed 25 future research questions were outlined, such as compare coaching models' level of effectiveness and what makes outcomes sustainable?
Bozer and Jones (2018)	Workplace coaching (both external and internal)	k = 117	Seven essential factors were identified: self-efficacy, coaching motivation, goal orientation, trust, interpersonal attraction, feedback intervention and supervisory support	15 future research questions were outlined, such as Is coaching motivation an affective outcome of workplace coaching? Is learning goal orientation an affective outcome of workplace coaching?

Meta-analysis
References	Coaching types	No. of papers	Main finings	Future suggestions
Theeboom et al. (2014)	Workplace coaching Both external and internal	k = 18	Effect sizes from g = 0.43 (coping) to g = 0.74 (goal-directed self-regulation)	A need for theoretical enrichment, such as self-determent theory (SDT), working alliance, characteristics of coaches and motivational components
Sonesh et al. (2015)	Executive, leadership and business coaching	k = 24	The impact of coaching on overall relationship outcomes was significant (g = 0.32, 95% CI [0.27, 0.38])	To what extent is coaching effectiveness attributable to positive shifts in coachees' relational and psychological states? What specific coach behaviors contribute to a strong positive coach-coachee relationship? What coach behaviors, strategies, and techniques contribute to successful coaching engagements?
Jones et al. (2016)	Workplace coaching Both external and internal	k = 17	Coaching had a positive effect on all outcomes (d = 0.36, 90% CI [0.16, 0.50]) Coaching had greater outcomes when coaching was provided without multisource feedback (d = 0.88 vs d = 0.21) Research design does not appear to moderate the effects of coaching on outcome coaching provided in the face-to-face format with blended formats The effects of coaching on outcomes were weaker for external coaches in comparison with internal coaches Neither longevity in weeks of the coaching intervention nor number of coaching sessions moderated overall coaching effectiveness	To examine cognitive, team or organizational-level results’ outcome criteria To examine how the relative impact of coaching on different kinds of criteria and compare this with other forms of L&D intervention (e.g. training) A need for the development of theory concerning why, how and in what ways coaching leads to the positive effects we reported in this study
Burt and Talati (2017)	Workplace and life coaching	k = 11	Coaching had a moderate significant positive effect on coachees, $\hat{p}$ = 0.42	The need for more performance rating and the coach–coachee relationship evaluation in the coaching literature A need to conduct longitudinal explorations and measure engagement across teams and the wider organizational level outcomes
Graßmann et al. (2020)	Workplace, life and career coaching	k = 27 (n = 3,563)	A moderate and consistent overall relationship between a high-quality working alliance and coaching outcomes for clients (r = 0.41, 95% CI [0.34, 0.48], p < 0.001)	To examine the role of the coaching relationship perspective in more detail
Systematic review
Lai and McDowall (2014)	Workplace, life and personal coaching	k = 140	Key factors for a positive coaching relationship were identified, such as building trust, two-way communication and transparent contracting process Essential attributes required for a professional coach in psychology area: theoretical knowledge (e.g. psychology and leadership), attitude (e.g. non-judgmental) and interpersonal skills	The future research should emphasize on the improvement of research methods and coaching result evaluation approaches to ensure producing more rigorous and replicable study results
Blackman et al. (2016)	Business coaching (external only)	k = 111	Coaching had positive effects on individual L&D outcomes There is no sufficient evidence to indicate coaching was more effective than other L&D approaches Key factors were identified to contribute to effective business coaching outcomes: the coach's (e.g. communication skills) and coachee's (e.g. self-efficacy) characteristics, coach–coachee relationship and organizational context Skills or expertise in the sector or in executive management were preferable	The future research should focus on developing sound theoretical models based on more sophisticated research
Grover and Furnham (2016)	Executive, leadership and business coaching (both external and internal)	k = 52	In general, coaching had positive effects on coachees' self-efficacy Coaching had positive effects on psychological outcomes, such as stress, anxiety, well-being, etc. There were mixed results between coaching and coachees' work or like satisfaction and performance Current research evidence indicated coaching generated longitudinal outcomes; however, more empirical research is required There was no adequate empirical evidence to confirm that coaching had positive impact on organizational-level outcomes Several mechanisms were identified: coachees' self-efficacy and motivation, coaches' interpersonal skills and the quality of coaching relationship, etc.	To establish an independent working group that consists of coaches, academics, organizations that use coaching and any stakeholders, and the research method should include methodological and statistical procedures, minimum sample sizes and a set of outcome variables
Athanasopoulou and Dopson (2018)	Executive coaching (external only)	k = 110	It is difficult to integrate the research evidence due to the diversity of research methods Social context and organizational-level outcomes have been overlooked in current research The research evidence on the effectiveness of coaching was not mixed	The future research should be a more context-sensitive based and better research designed 25 future research questions were outlined, such as compare coaching models' level of effectiveness and what makes outcomes sustainable?
Bozer and Jones (2018)	Workplace coaching (both external and internal)	k = 117	Seven essential factors were identified: self-efficacy, coaching motivation, goal orientation, trust, interpersonal attraction, feedback intervention and supervisory support	15 future research questions were outlined, such as Is coaching motivation an affective outcome of workplace coaching? Is learning goal orientation an affective outcome of workplace coaching?