Question: A researcher reviewed 500 medical records of children between the age of 8 and 12. He found that 50 of these children had a diagnosis of asthma. He selected 50 children without a diagnosis of asthma. For all 100 children in the study, he interviewed the family to determine whether there was an association between exposure to second-hand smoke and asthma. a) What type of study design is this? What is the most likely source of bias in this study design? Need Assignment Help?