In a certain noisy factory, workers are provided with earplugs and are expected to wear them.

In a certain noisy factory, workers are provided with earplugs and are expected to wear them. An industrial hygienist inspecting the plant found that 100 of the 500 workers in the factory were not wearing their earplugs because they regarded them as uncomfortable and as a nuisance. When all the workers are given a hearing test, it was found that 16 of the earplug wearers and 40 of the non-wearers had developed significant hearing loss. All had had normal hearing at their pre- employment examinations 4 years earlier, when the plant opened. (Hint: State a hypothesis before you tackle this problem.)

Would you please help clarify my doubts in bold as well? Thank you in advance!

2.1. What was the annual risk of hearing loss associated with not wearing earplugs? Wouldn’t this be calculated as 40/100?

2.2. What was the annual risk of hearing loss in those who wore earplugs?  Wouldn’t this be calculated as 16/400?

Now, assume that the study was conducted as a cross-sectional study. 

2.3. two-by-two table using the information provided. Includeanappropriatetitle, labels that identify each row and column, and row and column totals.

2.4. Compare the odds for hearing loss in nonwearers compared with wearers of earplugs?

Would you use the calculations from the first two questions to answer this question. If so, 

would the odds be 10 times higher regarding hearing loss in those who do not wear earplugs?

2.5. What conclusion do you draw from this comparison? Explain your answer in a sentence or two.