S0005 [Source: Ko et al. (2001). British Journal of Nutrition 85:239-242.]
A total of 5153 subjects (1419 men and 3734 women) from the Hong Kong community were examined. Their body mass index (BMI), body fat (BF) and other demographics were measured.
Males are defined as overweight and obese if their BF >= 20% and 30%, respectively; while females are defined as overweight and obese if their BF >= 30% and 40%, respectively. Using this definition, 113 (8.0%) men and 385 (10.3%) women were obese.
The study aimed to examine the use of BMI to define obesity as BF is measured by bioelectrical impedance which would need substantial resources if used in a community setting. When BMI >= 26.1 kg/m2 is used to define obesity of women, the accuracy was measured by
sensitivity, i.e. the proportion of truly obese women identified by using BMI, which was 90.4%; and
specificity, i.e. the proportion of truly non-obese women identified by using BMI, which was 89.2%.
Q1. Is the reported 10.3% of Hong Kong Chinese women a sample quantity or a population quantity?
Q2. Do you think the reported 10.3% of Hong Kong Chinese women were obese a trustworthy figure? Try to get an idea of how large the error can be in order to justify your conclusion.
Q3. What sample quantities may have an impact on the error in Q2.
Q4. Are the reported sensitivity and specificity sample quantities or population quantities?
Q5. How are the errors incurred in the reported sensitivity and specificity compared?