Remember that a confounding variable affects the response variable and is related to the explanatory variable. For each of the following situations, explain how the given confounding variable meets these criteria.

a. Response variable 5 Child’s IQ at age 10; explanatory variable 5 whether mother smokes or not; confounding variable 5 mother’s educational level.

b. Response variable 5 Number of missing or decayed teeth a child has; explanatory variable 5 amount of past exposure to lead; confounding variable 5 number of visits to a dentist the child has made in the past 3 years.