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For the following observational studies, indicate whether they are prospective or retrospective.
a) An airline was concerned that new security measures might discourage air travellers. They tracked the behavior of their frequent fliers after announcing new security restrictions to see whether frequent fliers flew fewer miles than they had before the restrictions.
b) Does giving children a flu shot protect parents? Researchers questioned a random sample of families at the end of a flu season. They asked whether the children had been immunized, whether the parents had received flu shots, and who in the family had contracted the flu.
