Durable press fabrics wrinkle less. The data in Exercise 24.35 show that durable press treatment greatly reduces the breaking strength of cotton fabric. Of course, durable press treatment also reduces wrinkling. How much? “Wrinkle recovery angle”

measures how well a fabric recovers from wrinkles. Higher is better. Here are data on the wrinkle recovery angle (in degrees) for the same fabric specimens discussed in the previous exercise:

Untreated 79 80 78 80 78 Permafresh 55 136 135 132 137 134 Permafresh 48 125 131 125 145 145 Hylite LF 143 141 146 141 145 The untreated fabric once again stands out, this time as inferior to the treated fabrics in wrinkle resistance. Examine the data for the three durable press processes and summarize your findings. How does the ranking of the three processes by wrinkle resistance compare with their ranking by breaking strength in Exercise 24.35?

Explain why we can’t trust the ANOVA F test.

Courtesy Blake Suttle