Table 4.

Effect sizes of different verbal interventions for postoperative pain relief

	Hypnosis (Kekecs 2014)30	Wake suggestions (Kekecs 2014)30	Intraoperative suggestions (Rosendahl 2016)13	Intraoperative suggestions (current study)
Pain	0.35*	0.13*	0.04*	0.45†
Opioids	0.23*	0.09*	0.16*	0.36†

Hedges’s g provides a correction of Cohen’s d when groups differ considerably in sample size. With similar sample size of the two groups in the present study, Hedges’s g and Cohen’s d are directly comparable.

^*Hedges’s g.

^†Cohen’s d.