Consider a group of 1,000 newborn infants. One hundred (100) infants were born with serious birth defects, and 20 of these 100 died during the first year of life. Ninety (90) of the 900 remaining infants without any birth defects also died during the first year of life.

If the crude RR is 2.0, and the stratum specific RRs are each 2.0, what is present?

If the crude OR is 3.45, and the stratum specific ORs are 2.0 and 2.1, what is present?