Hygiene of handshakes, high fives, and fist bumps. Refer to the American Journal of Infection Control (Aug. 2014) study of the hygiene of hand greetings, Exercise 9.24

(p. 479). The number of bacteria transferred from a gloved hand dipped into a culture of bacteria to a second gloved hand contacted by either a handshake, high five, or fist bump was recorded.

Recall that the experiment was replicated only five times for each contact method and the data used to compare the mean percentage of bacteria transferred for any two contact methods. Therefore, for this independent-samples design, n1 = n2 = 5. Suppose you want to estimate the difference between the mean percentage of bacteria transferred for the handshake and fist bump greetings to within 10% using a 95% confidence interval.

a. Define the parameter of interest in this study.

b. Give the value of za>2 for the confidence interval.

c. What is the desired sampling error, SE?

d. From the data provided in Exercise 9.24, find estimates of the variances, s1 2 and s2 2 , for the two contact methods.

e. Use the information in parts a–d to calculate the number of replicates for each contact method required to obtain the desired reliability. Assume an equal number of replicates.