In a study by Swedish researchers (Occupational and Environmental Medicine 2002, 59:517– 522), 2410 women who had worked as hairdressers and given birth to children were compared to 3462 women from the general population who had given birth. The hairdressers had a slightly higher percentage of infants with a birth defect.
a. Identify the response variable and the explanatory variable.
b. Is this study an observational study or an experiment? Explain.
c. Can we conclude that there’s something connected with being a hairdresser that causes higher rates of birth defects? Explain.