The article “Withdrawal Strength of Threaded Nails” (D. Rammer, S.Winistorfer, and D. Bender, Journal of Structural Engineering, 2001:442–449) describes an experiment comparing the withdrawal strengths for several types of nails. The data presented in the following table are consistent with means and standard deviations reported in the article for three types of nails: annularly threaded, helically threaded, and smooth shank. All nails had diameters within 0.1 mm of each other, and all were driven into the same type of lumber.

Nail Type

Withdrawal Strength (N/mm)

Annularly threaded

36.57 29.67 43.38 26.94 12.03 21.66 41.79 31.50 35.84 40.81

Helically threaded

14.66 24.22 23.83 21.80 27.22 38.25 28.15 36.35 23.89 28.44

Smooth shank

12.61 25.71 17.69 24.69 26.48 19.35 28.60 42.17 25.11 19.98

a. Construct an ANOVA table. You may give a range for the P-value.

b. Can you conclude that the mean withdrawal strength is different for different nail types?