Understanding evidence-based coaching through the analysis of coaching psychology research methodology

The interest in evidence-based coaching practice has been awakened since the beginning of this millennium; Grant’s literature review on coaching (Grant, 2001) was one of the pioneering studies to highlight the importance of psychological principles in coaching practice. Unlike other similar helping interventions (e.g. counselling and therapy), coaching is recognised as a cross-disciplinary intervention (such as management, psychology, social science, etc.). Therefore it is a big challenge to integrate the best available knowledge for evidence-based coaching practice. Several coaching related professional bodies (e.g. British Psychological Society, European Mentoring and Coaching Council, etc.) started to focus on defining the distinctions between coaching and other similar interventions because this is an essential step to identifying the most fitting principles for evidence-based coaching practice (Briner & Rousseau, 2011). Some special interest groups of coaching psychology were established (e.g. Interest Group Coaching Psychology by the Australian Psychological Society in 2002 and Special Group of Coaching Psychology by the British Psychological Society in 2004) to promote and strengthen psychological principles in coaching and coaching psychology practice. After more than a decade’s endeavour on the development of evidence-based coaching, the psychological standing in the coaching field was assured through three meta-analysis studies and four systematic reviews (Theeboom, Beersma, & van Vianen, 2014; Lai & McDowall, 2014; Jones, Woods, & Guillaume, 2015; Sonesh et al., 2015; Grover, & Furnham, 2016; Athanasopoulou, & Dopson, 2018; Bozer, & Jones, 2018). However, some evidence-based practice advocates still have doubts on the effectiveness of coaching interventions because the quality of the evidence is questioned (Briner, 2012). For instance, the majority of the coaching studies relied on qualitative research methods. However, randomised controlled trials (RCTs) are regarded as the most appropriate methodology to examine the effectiveness of interventions (Guyatt et al., 1995; Guyatt et al., 2000). Thus, the numbers of solid quantitative studies (e.g. trials with definite results) are expected to increase. According to Briner and Rousseau (2011), a systematic review (SR) which assesses all available evidence is identified as the most rigorous methodology for the evolution of evidence-based practice. Therefore, this chapter aims to provide an overview of up-to-date coaching psychology research evidence through synthesising two SRs on coaching psychology (Lai & McDowall, 2014; Lai, 2016). This analysis mainly scrutinises contemporary coaching research methodologies (1995–2016) and makes a comparison between two reviews. This will provide an in-depth understanding of the journey of evidence-based coaching in the past decade and identify future areas of research.