Many studies have found that children who listen to classical music while in the womb or when younger tend to have higher IQs later in life. These studies are typically done by surveying parents of older children about whether or not they played classical music when the child was younger and conducting an IQ test of the child.

a. Are these studies observational studies or experiments?
b. Will a cause-and-eff ect conclusion be possible?
c. Identify the observational units in these studies.
d. Identify the explanatory variable in these studies.
e. Identify the response variable in these studies.