Design of the Month

Folic acid

The following quotation is taken from page 13 of Metro on 13 May 2009.

Adding folic acid to bread could help cut the number of babies born with heart defects. There was a six per cent drop in the number of babies born with severe congenital heart problems after it became compulsory in Canada to fortify bread and pasta products with folic acid - also known as vitamin B9. And the results may have been underestimated because other factors known to cause heart problems - such as obesity - increased during the study from 1990 to 2005. `These findings support the hypothesis that folic acid has a preventive effect on heart defects,' researchers told the British Medical Journal.

  1. Was this a designed experiment, an observational study or a survey?
  2. What advantages did this study have?
  3. What disadvantages did this study have?
  4. For each of the other two types of study given in (1), explain how you would design one to investigate the topic which was investigated here.

Other designs

Page maintained by R. A. Bailey