Question

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.

Short answer

Part a. The chocolate consumption of the mother is the explanatory variable whereas the infants’ temperament is the response variable.

Part b. The study is an observational study.

Part c. No.

Step-by-step solution

Part a. Step 1. Explanation

The researchers want to determine if chocolate consumption during pregnancy had an effect on the infant temperament at an age of six months or not. Thus, the chocolate consumption is the independent variable whereas the temperament of the infants is the dependent variable as it depends on the chocolate consumption by their mothers during pregnancy. Therefore, the chocolate consumption of the mother is the explanatory variable whereas the infants’ temperament is the response variable.

Part b. Step 1. Explanation

In the given study, the researchers did not try to influence the mothers nor the infants. Moreover, the mount of chocolate consumption was decided by the mother’s itself and thus the researchers did not have control over the mother’s decisions.

The researchers thus did not assign treatments to the mothers for the study and therefore, this study is an observational study.

Part c. Step 1. Explanation

In part (b) we found out that the study was an observational study.

It is then not possible to find out if the chocolate consumption is the cause of infants’ temperament because the result could be affected by a lurking variable. A possible lurking variable is the mothers’ temperament as children tends to have the same temperament as their parents while the mothers’ temperament also influence how much chocolate they eat.

If we have to find out the accurate result then the experiment is better because the lurking variable does not influence it.