Meta-analyses of the effectiveness of MBSR in a variety of target groups, show medium effect sizes [ 18- 20].
However, all of them were only of medium effect sizes.
However, only small to medium effect sizes were found.
The power to detect medium effect sizes equal to 0.8 SD in the CO INTNtwo-groupup comparison was 91%.
Results reveal small to medium effect sizes for overall effects of age on L2A (d = 0.46 and Zr = −0.40).
Scores on most outcome measures changed in the predicted direction with medium effect sizes found for the functional outcomes.
Though not statistically significant, medium effect sizes favored the Headstrong group for headache duration and PedMIDAS at 3-months post-intervention by child ratings (both having ES = 0.70).
Significant differences were identified between groups in perseverative errors, perseverative responses, non-perseverative errors and unique errors in the Wisconsin Card Sorting Test (WCST) with medium effect sizes (Cohen's d ranging from 0.43 to 0.65).
Furthermore, BMI significantly lowered the number of non-specific skin conductance fluctuations and was negatively but not significantly associated with SCL and SCL standard deviation with small to medium effect sizes.
The studies by Brooks et al. (2010), Martino et al. (2008) and Kolur et al. (2006) all showed medium effect sizes (d = 0.47 to 0.68) but failed to find significant group differences.
Other factors with medium effect sizes showed White students to be more likely than minority students to identify their personal ambition as a motivation to persist and their self-confidence in understanding basic concepts in STEM.
