Statistical power is critical for theory-free, exploratory scans for G×E interactions (110). This realization has prompted the creation of large case-control consortia and massive biobanks. A question that puzzles many readers is how to reconcile the obvious benefits of huge samples with evidence that G×E interactions have been reported in many small-sample studies of 5-HTT and stress sensitivity, particularly in studies comparing stress-exposed versus matched nonexposed groups (e.g., abused children) and in experimental studies of humans and animals. There are statistical reasons for this.
