Sample size
MCI
The Montreal Cognitive Assessment (MoCA) score was used as the main indicator of this effect. Referring to the results of previous studies on the effects of Tai Chi and tDCS on cognitive function in patients with MCI, the predicted sample loss rate was ~20%. Using G-Power software with the effect size set at 0.3, power set at 0.8, and α set at 0.05, the calculated required sample size was at least 180 participants.