A University of Helsinki (Finland) study wanted to determine if chocolate consumption during pregnancy had an effect on infant temperament at age 6 months. Researchers began by asking 305 healthy pregnant women to report their chocolate consumption. Six months after birth, the researchers asked mothers to rate their infants’ temperament using the traits of smiling, laughter, and fear. The babies born to women who had been eating chocolate daily during pregnancy were found to be more active and “positively reactive”—a measure that the investigators said encompasses traits like smiling and laughter.

a. What are the explanatory and response variables?

b. Was this an observational study or an experiment? Justify your answer.

c. Does this study show that eating chocolate regularly during pregnancy helps produce infants with good temperament? Explain your reasoning.