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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: Hum Brain Mapp. 2010 Apr;31(4):499–514. doi: 10.1002/hbm.20882

Figure 7.

Figure 7

Sample size estimates with 80% power when mixing 1.5 T and 3 T scans. The lowest sample size number (n80), indicating greatest power, is found in the 1.5 T group when using the statistically-defined ROI based on 1.5 T scans. The worst performance arises when analyzing the 3 T scans using the 1.5 T-specific statistical ROI. Power can be increased in the 3 T group if a statistically-defined ROI based on 3 T scans is used instead, perhaps because some voxels with artifacts are avoided. Mixing 1.5 and 3 T scans does not affect the n80 adversely, and sample sizes for mixed scanner designs lie in between those using 1.5 or 3 T exclusively. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]