deletions | additions       diff --git a/I_was_not_clear_about__.tex b/I_was_not_clear_about__.tex  index ac58d3e..558f9fa 100644  --- a/I_was_not_clear_about__.tex  +++ b/I_was_not_clear_about__.tex 
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I was not clear about the overall goal of this project, which was not to claim that the method of scanning 12 phantom subjects travel is in any way cost effective! Rather, the goal was to measure MRI-related biases when systems are not standardized, and then see how we can overcome these biases with proper sample sizes, rather than our costly calibration method. If sites don't need to harmonize, they can include retrospective data in the analysis, which is certainly cost-effective because it has already been collected. Also, it allows sites the freedom to upgrade hardware/software or even change sequences during a study. This might be an incentive for sites to contribute data even if they are given little financial incentive, because it requires very little effort on their part! I We  focused too much on the phantom calibration aspect when actually I we  should have emphasized our statistical model that accounts for MRI-related biases, the measurements of that bias (which were estimated and validated via calibration), and the idea that this is an alternative method to ADNI harmonization, rather than a strict improvement. The phantom calibration is still important to show that when you apply our assumption of scaled bias to our measurements, the overall absolute agreement between sites improves to the same level of ADNI harmonization. I follow up on this in my response to the next revision, which compares our results to other harmonization efforts.