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Table 1 Comparison of study categories

From: The rise of large-scale imaging studies in psychiatry

Category Comparability across datasets or sources Control over analyses1 Depth of phenotyping available Ease of collecting a large sample2
Planned studies Highest possible similarities in data Highest Can be very deep but specific to the study hypotheses Most difficult
Aggregated mega-analyses Moderate; Some filtering of available datasets for improves comparability High Low to Moderate Moderately easy; it requires existing datasets and investigators willing to share them
Opportunistic studies Moderate, but can be high if scanning centers agree to use minimal standard protocols High Moderate Moderately difficult; it often requires institutional arrangements to get started
Meta-analyses (post-hoc) Lowest Lowest Lowest Easiest; all published results that fit the meta-analytic question are available
Meta-analyses (prospective) Lowest High Lowest Moderate; it requires existing datasets and teams to analyze them in collaboration
  1. 1: Control over analyses covers whether planned analyses across each subset of the dataset are done the same way, either by a central authority or planned and agreed upon across groups performing the analyses.
  2. 2: Ease refers in a general way to the efforts involved in design and calibration, data aggregation and analysis, apart from study specific issues of the particular clinical population or obtaining any necessary funding, for example.