An eighth-grade student in Canada was concerned that air dryers in public restrooms were too loud, especially when measured at the height of children’s ears. Her results were eventually published in Pediatrics & Child Health (Keegan, 2019). Thinking that having your hands under the dryer might make a difference in the sound intensity, she took measurements with hands under the dryer and without hands under the dryer. The results, in A-weighted decibels (dBA), from 22 different makes and models of air dryers taken at the author’s ear height can be found in the file AirDryers2. We want to test to see whether, on average, there is difference in the sound intensity between having hands under the dryer and not having hands under the dryer. Put the data in the Matched Pairs applet to answer (a)–(e). 

a. Explain why the data should be treated as paired, not independent. 

b. What are the mean dBA measurements for the two conditions? Which results in a larger average sound intensity? 

c. What is the average difference in sound intensity (hands – no hands)? 

d. Appropriately randomize at least 1,000 times and determine a p-value. 

e. Is there strong evidence that, on average, there is a difference in the sound intensity between having hands under the dryer and not having hands under the dryer?