Question

An investigator was interested in the effect of a nutritionally poor diet during pregnancy on the likelihood of brain defects. She realized it would be unethical to take a group of pregnant women and assign half of them to a condition in which they would consume a nutritionally inadequate diet. She chose instead to collect data on the nutritional adequacy of the mother's diet and the occurrence of a birth defect of all children born in the hospitals of a large city for one month.

a. What sort of scientific study would she be using?
b. If the two variables are significantly related, can she conclude that the children's birth defects are caused by the mother's nutritionally inadequate diet? Explain your answer.

Answer 1

The investigator is conducting an observational study, which is appropriate when assigning variables to test outcomes is not practical or ethical. Although a significant relationship would suggest a correlation between poor maternal nutrition and brain defects, it does not establish causation.

Step-by-step explanation:

The investigator is using an observational study to collect data on the nutritional adequacy of mothers' diets and the occurrence of brain defects in their children. This type of study is chosen because assigning variables to test outcomes, such as a poor diet during pregnancy, is not practical or ethical in this case.

If the study finds that poor maternal nutrition and brain defects in children are significantly related, the investigator cannot conclusively claim causation. A significant relationship suggests a correlation, but this does not establish that the nutritionally inadequate diet caused the brain defects. Other factors, also known as confounding variables, could be influencing the results. Nonetheless, the correlation found can be important for guiding further research and hypothesis formation.