We investigate the relationships between scan duration, signal-to-noise ratio (SNR) and group-level variance in GABA-edited MRS. Typically, GABA editing takes ~10 min for a 27-mL voxel. GABA+/Cr measurements from five voxels from 18 participants were analyzed by cumulatively binning the averages within each dataset to determine the effects on SNR and group-level variance. Sample size calculations estimated the required sample sizes needed for different predicted effect sizes in GABA-edited MRS studies. We show that the duration of GABA-edited acquisitions can be reduced if taking into account a statistically acceptable amount of group-level variance and the magnitudes of predicted effects.