The effectiveness of psychological skills training and behavioral interventions in sport using single-case designs: A meta regression analysis of the peer-reviewed studies
Sport psychology single-case studies show big gains, but sloppy baselines and missing reliability checks inflate the numbers.
01Research in Context
What this study did
Barker et al. (2020) pooled every single-case sport psychology paper they could find.
They used meta-regression to see how big the effects really are and what flaws make them look bigger.
What they found
The average effect looked huge, but short baselines and missing reliability checks pumped it up.
In plain words: the gains are probably real, just smaller than the papers claim.
How this fits with other research
Matson et al. (2004) counted 40 single-case sport studies and said "we need more." Barker shows we also need cleaner.
Schenk et al. (2019) mapped 101 behavioral sport papers; Barker zooms in on the single-case slice and spots the wobble.
Shadish et al. (2016) asked researchers if they chase big effects—some said yes. Barker’s inflated numbers prove the chase worked.
Why it matters
Before you copy a "proven" golf routine or relaxation script, check the baseline length and if two people scored the videos. If those pieces are missing, scale your expectations down and run your own quick reliability check. Better data equals cooler heads and smoother buy-in from coaches.
Get CEUs on This Topic — Free
The ABA Clubhouse has 60+ on-demand CEUs including ethics, supervision, and clinical topics like this one. Plus a new live CEU every Wednesday.
Add five stable baseline days and have a second observer score at least 20% of your athlete’s video clips.
02At a glance
03Original abstract
We used a novel meta regression analysis approach to examine the effectiveness of 24psychological skills training and behavioral interventions in sport assessed using single-case 25experimental designs (SCEDs). One hundred and twenty-one papers met the inclusion criteria 26applied to eight database searches and key sport psychology journals. Seventy-one studies 27reported sufficient detail for effect sizes to be calculated for the effects of psychological skills 28training on psychological, behavioral, and performance variables. The unconditional mean 29effect size for weighted (∆ = 2.40) and unweighted (∆ = 2.83 ) models suggested large 30improvements in psychological, behavioral, and performance outcomes associated with 31implementing cognitive-behavioral psychological skills training and behavioral interventions 32with a SCED. However, meta-regression analysis revealed important heterogeneities and 33sources of bias within this literature. First, studies using a group-based approach reported 34lower effect sizes compared to studies using single-case approaches. Second, the single-case 35studies, (over 90 per cent the effect sizes), revealed upwardly biased effect sizes arising from: 36(i) positive publication bias such that studies using lower numbers of baseline observations 37reported larger effects, while studies using larger numbers of baseline observations reported 38smaller – but still substantial – effects; (ii) not adopting a multiple baseline design; and (iii) 39not establishing procedural reliability. We recommend that future researchers using SCED’s 40should consider these methodological issues. 41Keywords: meta regression analysis, psychological skills training, single-case experimental 42designs, procedural reliability, applied sport psychology
Psychology of Sport and Exercise, 2020 · doi:10.1016/j.psychsport.2020.101746