Two investigators were interested in testing the hypothesis that high educational attainment is associated with more frequent unintentional injuries in the home.
To test their hypothesis the investigators selected a random sample of 5,000 men and women, 21 years of age and older, living in owner-occupied, single-family dwellings in Seattle, Washington, during February 2002.
Data were also collected on potential confounders, such as age, sex, income level, and health status. The results of this cross-sectional study were as follows:
• 10% of the sample had high educational attainment (defined as a college degree or higher) and unintentional injuries in the home in the previous 12 months
• 10% of the sample had high educational attainment but no unintentional injuries in the home in the previous 12 months
• 20% of the sample had low educational attainment (defined as having less than a college degree) and unintentional injuries in the home in the previous 12 months
• 60% of the sample had low educational attainment but no unintentional injuries in the home in the previous 12 months
Based on this information, calculate and interpret the prevalence rate ratio and its 95% confidence interval. Assuming that the study was designed to minimize bias and confounding, was the investigators' hypothesis supported, and why or why not?