Measuring Treadwear. R. Stichler et al. compared two methods of measuring treadwear in their paper “Measurement of Treadwear of Commercial Tires” (Rubber Age, 73:2). Eleven tires were each measured for treadwear by two methods, one based on weight and the other on groove wear. The following are the data, in thousands of miles.

Weight Groove Weight Groove method method method method 30.5 28.7 24.5 16.1 30.9 25.9 20.9 19.9 31.9 23.3 18.9 15.2 30.4 23.1 13.7 11.5 27.3 23.7 11.4 11.2 20.4 20.9 At the 5% significance level, do the data provide sufficient evidence to conclude that, on average, the two measurement methods give different results?