A crossover study of 13 children suffering from asthma (Clinical and Experimental Allergy, vol. 20, pp. 429€“432, 1990) compared single inhaled doses of formoterol (F) and salbutamol (S). The outcome measured was the child€™s peak expiratory flow (PEF) 8 hours following treatment. The data on PEF follow:

Let μ denote the population mean of the difference between the PEF values for the F and S treatments. Use a calculator or software for the following analyses:
a. Form the 13 difference scores, for instance 310 - 270 = 40 for child 1 and 330 - 365 = -35 for child 9, always taking F - S. Construct a dot plot or a box plot. Describe the sample data distribution.
b. Carry out the five steps of the significance test for a mean of the difference scores, using H0: μ = 0 and Ha: μ ‰  0.
c. Discuss whether or not the assumptions seem valid for this example. What is the impact of using a convenience sample?

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Child F SChild FS ChildFS Child F S 310 270 5 410 380 9 330 365 13 220 90 2 385 370 6 370 300 10 250 210 3 400 310 7 410 30 11 380 350 4 310 260 8 320 290 12 340 260