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Text: The cases sometimes had subtle manifestations of hemi-facial macrosomia, so the pediatricians who identified these cases were perhaps more skilled at identifying it. The investigators identified the cases and then contacted the referring pediatrician, asking for their help in finding controls. The pediatricians were asked to identify ten patients seen by them during the same week that the case had been seen, but the controls were seen for reasons other than facial microsomia. Out of the ten candidate controls they hoped they could find four parents who were willing to complete the questionnaire on potential risk factors. Therefore, this strategy perfectly fulfilled the "would" criterion, since, if a control had had hemifacial microsomia, it is likely they "would" have ended up in the case group, , since the pediatrician was not only astute in recognizing the subtle deformity, but also would have referred such patients to the same tertiary care hospital.